Soft law in the Paris Climate Agreement: Strength or weakness?

AuthorPeter Lawrence,Daryl Wong
Date01 November 2017
Published date01 November 2017
RECIEL. 2017;26:276–286.
DOI: 10.1111/reel.12210
Soft law in the Paris Climate Agreement: Strength or
Peter Lawrence | Daryl Wong
© 2017 John Wiley & Sons Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA.
Email: In the lead- up to the Paris Agreement, and in reactions to it since its adoption, there
has been a narrative which emphasizes the perceived advantages of key mitigation
obligations in the Agreement being non- binding or ‘soft’ law. Central to these advan-
tages is the idea that soft law obligations were a precondition for United States, China
and wider participation in the Agreement, and also desirable in terms of flexibility. This
article challenges the soft law narrative, arguing that the Paris Agreement’s use of
non- binding ‘nationally determined contributions’ has come at a cost in terms of likely
effectiveness. Empirical studies comparing hard (binding) and soft law obligations in
terms of compliance and effectiveness are equivocal, but precision of obligations and
effective non- compliance mechanisms are essential. Moreover, when States have a
strong political will to change behaviour, treaty instruments containing hard obliga-
tions have been considered to be more likely to be effective (e.g., ozone agreements,
World Trade Organization agreements and arms control treaties). The development of
the transparency, review and non- compliance elements of the Paris Agreement is es-
sential, but is no substitute for strong political will to reduce emissions. In addition, it
is crucial to muster the political will to ratchet up the Paris mitigation commitments
and transform them from soft to hard obligations. The article assesses options for
doing this, including a Conference of the Parties decision and a political declaration.
The Paris Agreement on climate change has been widely applauded.1
On the adoption of the Agreement, United Nations Secretary- General
Ban Ki- moon stated: ‘Today you are signing a new covenant with the
future.’2 Undoubtedly, obtaining agreement in Paris was a triumph of
diplomatic skill. However, a sober analysis of key provisions of the
Paris Agreement relating to the mitigation of greenhouse gas emis-
sions raises serious concerns in terms of its potential effectiveness.
Our concern centres on the role of ‘soft’ non- binding mitigation obliga-
tions in the Agreement. In the lead- up to Paris, and in responses since,
there has been a strong narrative emphasizing the advantages of key
mitigation obligations in the Agreement being non- binding (or ‘soft
law’). Central to these advantages is the notion that non- binding obli-
gations were a precondition for the United States’ (US) participation
and ultimate ratification, which in turn was seen as a precondition for
other key players such as China coming on board. Soft obligations
were also seen as desirable in terms of flexibility, and the possibility of
ratcheting up obligations quickly over time. But this narrative was
challenged by countries in the lead- up to Paris – including by the
European Union (EU) and countries who are most likely to be seriously
impacted by climate change (e.g., the small island States and many
African countries) – who argued that an effective agreement had to be
hard law with binding mitigation commitments.3
22 April 2016, entered into force 4 November 2016)
ground/convention/application/pdf/english_paris_agreement.pdf> (Paris Agreement).
2ABC News, ‘Paris Agreement: More than 170 World Leaders Sign United Nations Climate
Deal’ (ABC News 23 April 2016).
3R Byrnes and P Lawrence, ‘Can “Soft Law” Solve “Hard Problems”? Justice, Legal Form and the
Durban- Mandated Climate Negotiations’ (2015) 34 University of Tasmania Law Review 34, 41ff.
Ultimately, the ‘pro- soft law’ narrative largely won the day in Paris.
While the Paris Agreement is clearly a legally binding treaty,4 its key miti-
gation obligations5 – which relate to the fulfilment and form of nationally
determined contributions (NDCs)6 – remain voluntary.7 Further, the
Agreement’s provisions on non- compliance are very weak. The Paris
Agreement represents the latest phase in a decisive shift in global climate
governance away from binding (hard) obligations and a notion of redis-
tributive justice, towards a governance model that emphasizes voluntary
commitments and ‘self- differentiation’ of obligations.8 This shift is
strongly linked to neoliberal principles that have dominated global
governance over recent decades.9 This new notion of climate governance
was strongly reflected in the Durban mandate and, ultimately, in the Paris
Agreement itself.10
This article challenges the pro- soft law narrative, and in partic-
ular the assumption that having soft law mitigation commitments
would not compromise the effectiveness of the Agreement. Although
these commitments may have helped ensure wide participation in the
Paris Agreement and the approach adopted was arguably the only
politically feasible one at the time, the soft mitigation obligations of
the Agreement also represent a serious weakness of the Agreement,
and come at a cost in terms of its likely compliance and ultimate effec-
tiveness. The article makes a distinctive contribution to the literature
by: (i) linking the question of whether to adopt hard or soft law com-
mitments to empirical studies; (ii) discussing whether the transpar-
ency, review and non- compliance provisions in the Paris Agreement
(hereafter collectively ‘review provisions’) can make up for the lack
of bindingness in the NDC mitigation provisions; and (iii) analysing
possibilities for hardening the obligations contained within the Paris
Agreement over time.
Empirical studies, comparing hard (binding) and soft law obliga-
tions in terms of compliance and effectiveness to date, have tended to
be equivocal, with few studies examining soft obligations within a
binding treaty (‘treaty soft law’) similar to that found in the Paris
Agreement as a sui generis category. Precision in obligations has cor-
related, however, with strong levels of compliance and, as we will see,
the Paris Agreement is problematic in allowing for NDCs that may be
deficient due to a lack of precision. Moreover, it is striking that when
States wish to ensure changes in behaviour, treaty instruments con-
taining hard obligations have been considered to be more likely to be
effective (e.g., ozone agreements, World Trade Organization (WTO)
agreements and arms control treaties). Part of the reason for this is
that hard – and precise – obligations tend to correlate with effective
compliance mechanisms.11 Another reason relates to the fact that
treaty- level norms usually require domestic constitutional processes
that do not apply to soft instruments or soft norms.
An important caveat to the propositions above: the soft commit-
ments in the Paris Agreement may, in spite of their non- legally binding
status, have impacts over time by changing behaviour in ways which
are not captured by a narrow focus on compliance with international
legal obligations as traditionally understood. Van Asselt points out that
the Paris Agreement may offer important ‘signals’, including the need
to transform the global economy to a carbon- neutral one by 2050,
which may be taken up by non- State actors including business or insti-
tutions pushing for fossil fuel divestment.12 Our analysis does not ex-
clude such possibilities. We argue, however, that given the urgency of
strong mitigation action in response to climate change science, such
positive effects could be further magnified by ratcheting up the legal
status of the mitigation elements of the Paris Agreement over time to
help ensure its effectiveness.
To achieve the latter objective, we analyse options for trans-
forming the soft obligations of the Paris Agreement into hard obliga-
tions. These options include: (i) a declaration; and (ii) a Conference
of the Parties (COP) decision. These options are analysed both in
terms of how they will contribute to the effectiveness of the
Agreement as it evolves over time, but also in terms of their political
First, some key definitions. The key criterion for the assessment
undertaken here is ‘effectiveness’ defined in terms of the Paris
Agreement’s goal of ‘[h]olding the increase in the global average tem-
perature to well below 2 °C above pre- industrial levels and to pursue
efforts to limit the temperature increase to 1.5 °C above pre- industrial
levels’.14 The extent to which a particular treaty is effective in address-
ing a particular problem is a product of both the quality and stringency
of its obligations, the level of participation in the Agreement and the
extent of compliance with the treaty obligations in question.15
4S Oberthür and R Bodle, ‘Legal Form and Nature of the Paris Outcome’ (2016) 6 Climate Law
40, 42–46. Whether a particular agreement constitutes a treaty binding under international
law, depends on the intention of the parties. See Case Concerning the Frontier Dispute (Burkina
Faso v Republic of Mali) (Judgment) [1986] ICJ Rep 69, para 39 (Burkina Faso v Republic of Mali).
Parties to the Paris Agreement clearly intended it to be legally binding. This is evidenced by
the use of mandatory language in the Agreement (e.g., reference to ‘agreement’ rather than
‘understanding’) and also the inclusion of provisions relating to entry into force, depository,
reservations and amendments; see Paris Agreement (n 1) art 20–22, 26–27.
5Namely, Paris Agreement (n 1) art 4, to be discussed below.
6Which are tied to a good faith expectation that parties ‘intend to’ and ‘aim’ to achieve the
objectives of their NDCs. See L Rajamani, ‘Ambition and Differentiation in the 2015 Paris
Agreement: Interpretive Possibilities and Underlying Politics’ (2016) 65 International and
Comparative Law Quarterly 493, 497–498.
7The Agreement does have good faith and procedural obligations, which will be discussed
8J McGee and J Steffek, ‘The Copenhagen Turn in Global Climate Governance and the
Contentious History of Differentiation in International Law’ (2016) 27 Journal of
Environmental Law 37.
9ibid, consider this historical shift in the broader context of global governance, including out-
side the domain of environmental agreements. For other perspectives on how differentiation
is reflected in the Paris Agreement, see Rajamani (n 6) and C Voigt and F Ferreira,
‘Differentiation in the Paris Agreement’ (2016) 6 Climate Law 58.
10McGee and Steffek (n 8) 41.
11It has been recognized that a compliance mechanism, such as the Kyoto Protocol
Compliance Committee’s Enforcement Branch, which had the power to penalize States for
exceeding their emissions limit, may even be necessary given the binding nature of the emis-
sions obligations. A Zahar, ‘A Bottom- Up Compliance Mechanism for the Paris Agreement’
(2017) 1 Chinese Journal of Environmental Law 69.
12H van Asselt, ‘International Climate Change Law in a Bottom- Up World’ (2016) 6 Questions
of International Law 5. Van Asselt’s analysis is inspired by R Howse and R Teitel, ‘Beyond
Compliance: Rethinking Why International Law Really Matters’ (2010) 1 Global Policy 127.
13An amendment of the Paris Agreement is not considered in this article, as it is not likely to
be politically feasible – at least in the short term – given the enormous investment into the
negotiation of the Agreement itself.
14Paris Agreement (n 1) art 2(1).
15D Bodansky, ‘The Durban Platform: Issues and Options for a 2015 Agreement’ (Center for
Climate and Energy Solutions 2012); see also G Bang, J Hovi and T Skodvin, ‘The Paris
Agreement: Short- Term and Long- Term Effectiveness’ (2016) 4 Politics and Governance 209,
who distinguish between short- and long- term effectiveness.
Therefore, while the Paris Agreement is framed to ensure broad
participation, it is the quality and stringency of its obligations and its
likely compliance that are problematic, and not the overarching goal.
Commentators generally accept that the overarching goal of the Paris
Agreement is well calibrated with effectiveness, in terms of prevailing
climate change science. However, even if fully implemented, the first
round of NDCs which contain individual countries’ commitments to
reduce greenhouse gas emissions seems set to permit emissions well
over 2 °C.16
We use the term ‘soft law’ as a shorthand to refer to obligations
that are not legally binding under international law, as opposed to
‘hard law’ obligations, which are. This of course, implies a concept of
law. Some scholars, such as Brunnée and Toope, have challenged the
idea of there being a sharp distinction between hard and soft law,
arguing that there are degrees of ‘bindingness’ in relation to obliga-
tions found in international agreements, showing that soft and hard
law operate over a continuum.17 However, the assumption in this arti-
cle is that States continue to maintain a distinction between obliga-
tions that are binding under international law and those that are not.
As pointed out by Bothe, States indicate through their behaviour that
this matters and they ‘argue about it’.18 For the purposes of this article,
we consider soft law to refer to non- legally binding rules made by
States and other subjects of international law (that can have legal ef-
fect19 or ‘special legal relevance’).20 By hard law obligations we refer to
obligations that are legally binding.21
But ‘bindingness’ of obligations tells us only part of the story. Of
equal importance is whether provisions are sufficiently precise to con-
strain States.22 Thus, our analysis focuses not only on whether individ-
ual mitigation provisions of the Agreement create legal obligations, but
also whether they are sufficiently precise to constrain States in their
behaviour.23 In doing so, we do not analyse the soft/hard nature of
commitments across the entire Paris Agreement, but we focus on the
provisions that relate to the mitigation of greenhouse gas emissions,
including the overarching objectives of the Agreement, provisions on
NDCs and provisions related to review and compliance provisions.
The article is structured as follows. We first assess the extent to
which mitigation obligations in the Paris Agreement are hard or soft.
We then turn to the question of whether the choice of hard or soft
obligations matters in terms of effectiveness. This is addressed by
briefly surveying existing empirical studies on this question. We go
on to discuss whether having an effective compliance mechanism is
dependent on having primary obligations that are binding. Next, we
examine whether the effectiveness of the soft mitigation commitment
obligations in the Paris Agreement are overcome by the review provi-
sions of the Agreement (including its related transparency and non-
compliance provisions). We then explore whether the soft law nature
of mitigation commitments in the Paris Agreement could be strength-
ened over time, including through a COP decision or a declaration by a
particular group of countries. In our conclusions, we indicate possible
areas for future research in this field.
2.1 | Negotiations leading up to the Paris Agreement
The mitigation commitments in the Paris Agreement reflect both the
Durban mandate under which the Paris Agreement was negotiated,
and also the negotiation dynamic leading up to adoption of the Paris
Agreement.24 The 2011 Durban negotiation mandate provided that
parties would develop ‘a protocol, another legal instrument or an
agreed outcome with legal force under the Convention applicable to
all parties’.25 While the terms ‘protocol, another legal instrument …
applicable to all parties’ were generally interpreted as referring to a
treaty- status instrument binding under international law, the
additional words ‘agreed outcome with legal force’ seemed to envis-
age another category of instrument, which could include a soft law
outcome.26 The reference to ‘agreed outcome with legal force’ was
inserted at India’s insistence.27 India argued that the Durban Platform
should not be a vehicle for imposing mitigation burdens on developing
countries, as this would involve reinterpreting the United Nations
Framework Convention on Climate Change (UNFCCC), and in particu-
lar would violate the principle of common but differentiated
16The potential increase above 2 °C includes a range of values up to 3 °C, depending on the
implementation levels of conditional and unconditional NDCs. See United Nations
Environmental Programme (UNEP), The Emissions Gap Report 2016 (UNEP 2016) xviii; see also
J Rogelj et al, ‘Discrepancies in Historical Emissions Point to a Wider 2020 Gap between 2 °C
Benchmarks and Aggregated National Mitigation Pledges’ (2011) 6 Environmental Research
Letters 024002. However, note that negotiating parties recognized the need to set an ambi-
tious goal to get to the maximum level of ambition to close the gap between the current
emissions trajectory and where the science indicates we need to be; see United Nations
Regional Information Centre for Western Europe, ‘Figueres: First Time the World Economy is
Transformed Intentionally’ (3 February 2015)
17J Brunnée and SJ Toope, ‘Persuasion and Enforcement: Explaining Compliance with
International Law’ (2002) 9 Finnish Yearbook of International Law 27; KW Abbott and D
Snidal, ‘Hard and Soft Law in International Governance’ (2000) 54 International Organization
18M Bothe, ‘Legal and Non- legal Norms – A Meaningful Distinction in International Relations?’
(1980) 11 Netherlands Yearbook of International Law 65, 94. However, there can be complex
interrelationships between ‘hard’ and ‘soft’ obligations and the classification of particular ob-
ligations using the traditional sources of international law can be challenging. See C Chinkin,
‘The Challenge of Soft Law: Development and Change in International Law’ (1989) 38
International and Comparative Law Quarterly 850.
19J Pauwelyn, ‘Is it International Law or Not, and Does it Even Matter?’ in J Pauwelyn, R
Wessel and J Wouters (eds), Informal International Lawmaking (Oxford University Press 2012)
125, 145–155.
20D Thurer, ‘Soft Law’ in R Wolfrum (ed), Max Planck Encyclopaedia of Public International Law
(Oxford University Press 2009) 3.
21The test for bindingness is determined by reference to whether States intended the obliga-
tion to be legally binding: see Burkina Faso v Republic of Mali (n 4) para 39.
22One enters the realm of soft law when one or more of the following dimensions are weak-
ened: ‘obligation’, ‘precision’ or ‘delegation’. Abbott and Snidal (n 17) 422.
23Oberthür and Bodle (n 4) 48–51.
24This section draws on Byrnes and Lawrence (n 3).
25UNFCCC ‘Decision 1/CP.16, The Cancun Agreements: Outcome of the Work of the Ad Hoc
Working Group on Long- Term Cooperative Action under the Convention’ UN Doc FCCC/
CP/2010/7/Add.1 (15 March 2011); for further discussion of the negotiations leading up to
the Paris Agreement, see Rajamani (n 6).
26R Moncel, ‘Unconstructive Ambiguity in the Durban Climate Deal of COP 17/CMP 7’ (2011)
12 Sustainable Development Law and Policy 6, 7.
27L Rajamani, ‘The Durban Platform for Enhanced Action and the Future of the Climate
Regime’ (2012) 61 International and Comparative Law Quarterly 501, 506.
responsibilities (CBDR), which places an obligation on developed
countries to take the lead in reducing emissions.28
The EU,29 the Alliance of Small Island States,30 the African Group
and some developed countries31 argued during the Paris Agreement
negotiations that a strong climate agreement would need to be legally
binding in form, with similarly legally binding mitigation commit-
ments. A significant number of developing countries took this
position with the qualification that only developed countries should
take on such binding commitments.32 Many developing country par-
ties also insisted that mitigation efforts by developing countries
should be conditional on financial assistance from developed par-
ties.33 This approach was driven by the belief that binding legal com-
mitments would promote effectiveness even in the absence of judicial
enforcement, or promote the appearance of effectiveness to the gen-
eral public.34
A key factor in the negotiations was the position of the US. Given
the Republican domination of the Senate, the US position was to avoid
any instrument that would require Senate approval. It thus required an
agreement that it could ratify on the basis of the President’s executive
power. This meant that it could only accept voluntary, non- binding
mitigation commitments.35 With the recent announcement of
President Trump stating the country’s intention to withdraw from the
Paris Agreement, the wisdom of this strategy appears questionable in
hindsight. However, at the time of the Paris negotiations it was by no
means inevitable that Trump would win the US election. Interestingly,
the negotiators did seek to ‘Trump proof’ the Agreement by requiring
any withdrawal to not become effective until three years from the date
of entry into force for that party.36 A Paris Agreement with binding
mitigation obligations with respect to NDCs might have been more
difficult for the US to withdraw from,37 but the US would very likely
not have become a party to such an agreement in the first place.
During the negotiations, Japan, the US and China, and eventually
India, came to favour an approach that involved a binding core agree-
ment, but with mitigation commitments outside the agreement in sep-
arate non- binding NDCs.38 It is this approach, reflective of the pro- soft
law narrative,39 that eventually prevailed in the final text of the Paris
Agreement, with its substantive mitigation provisions reflecting a
‘treaty soft law’ model.40
2.2 | Compromise in the Paris Agreement
We now turn to examining the precise status of the key mitigation com-
mitments in the Paris Agreement. This involves an analysis of the vari-
ous obligations associated with NDCs, both procedural and substantive.
Critical here is how NDCs are linked or anchored to the Agreement and
its broader objectives. The Paris Agreement provisions relating to trans-
parency, review and non- compliance are considered below.
The objective of the Paris Agreement, as noted above, is to hold
average global warming to 2/1.5 °C. To achieve this, the Agreement states
that ‘Parties aim to reach global peaking of greenhouse gas emissions as
soon as possible, … so as to achieve a balance between anthropogenic
emissions by sources and removals by sinks of greenhouse gases in the
second half of this century’.41 This overarching statement of objective is
couched in non- legally binding terms as a collective goal. Importantly, it
sets the context for the more specific obligations relating to mitigation.
The second and third paragraphs of Article 4 of the Paris Agreement con-
tain the key obligations relating to NDCs and are worth quoting in full:
2. Each Party shall prepare, communicate and maintain successive
nationally determined contributions that it intends to achieve.
Parties shall pursue domestic mitigation measures, with the aim
of achieving the objectives of such contributions.
3. Each Party’s successive nationally determined contribution will
represent a progression beyond the Party’s then current na-
tionally determined contribution and reflect its highest possible
ambition, reflecting its common but differentiated responsibili-
ties and respective capabilities, in the light of different national
The nature of the Paris Agreement obligations related to NDCs
needs to be considered in the context of their origins. The idea of NDCs
flowed from the Copenhagen Accord agreed at the 2009 UNFCCC COP.
28‘Submission by India on the Work of the Ad- Hoc Working Group on the Durban Platform
for Enhanced Action: Workstream I’ (13 September 2013)
workstream_2_2030309.pdf> 2.
29‘Submission by Italy and the European Commission on Behalf of the European Union and its
Member States’ (14 October 2014)
sion.pdf> 3, 7.
30‘Statement by Maldives on Behalf of the Alliance of Small Island States at the Opening
of the Ad Hoc Working Group on the Durban Platform for Enhanced Action, Bonn,
Germany’ (3 June 2015) /
oad/211_129_130897438389200212-ADP%20Opening%20Statement_19_10.pdf> 2.
31‘New Zealand, Submission to the Ad Hoc Working Group on the Durban Platform for
Enhanced Action: Work Stream 1’ (8 October 2014)
ments_-__october2014.pdf> 3; ‘Australia, Submission under the Durban Platform for
Enhanced Action’ (26 March 2013)
from_parties/adp/application/pdf/adp_australia_workstream_1_20130326.pdf> 4.
32See, e.g., ‘Views of Brazil on the Elements of the New Agreement under the Convention
Applicable to All Parties’, Submission to the ADP (6 November 2014)
ADP%20Elements.pdf> 3.
33See, e.g., Submission by India (n 28) 4.
34D Bodansky, ‘The Legal Character of the Paris Agreement’ (2016) 25 Review of European,
Comparative and International Environmental Law 142, 149.
35D Bodansky, ‘Legal Options for US Acceptance of a New Climate Agreement’ (Centre for
Climate and Energy Solutions 2015) 29.
36Paris Agreement (n 1) art 28; see also L Kemp, ‘US- Proofing the Paris Climate Agreement’
(2017) 17(1) Climate Policy 86.
37But see N Feldman, ‘The Paris Accord and the Reality of Presidential Power’ (Bloomberg
View 2 June 2017)
38Oberthür and Bodle (n 4) 44–47.
39For an example of literature emphasizing the flexibility involved with soft law NDCs, see S
Maljean- Dubois, M Wemaëre and T Spencer, ‘A Comprehensive Assessment of Options for
the Legal Form of the Paris Climate Agreement’ (Institute for Sustainable Development and
International Relations (IDDRI) 2015) 9.
40However, it is by no means clear that States chose this option because of a view that soft
law is superior in terms of compliance or otherwise; see further Bothe (n 18) 94; and Chinkin
(n 18) 850–866.
41Paris Agreement (n 1) art 4(1).
42ibid art 4(2–3).
In this decision, State parties to the UNFCCC were to decide for them-
selves on a voluntary national target – with a list of these targets com-
piled by the UNFCCC Secretariat.43 In the negotiations leading up to the
Paris Agreement, it became clear that a similar idea (described first as
intended nationally determined contributions, or INDCs) would be used
for the basis of mitigation commitments in the Paris Agreement.44
However, it was unclear, until the negotiations were concluded in Paris,
how such INDCs would be linked to the Paris Agreement.45
It would have been possible to make NDCs binding by appropriate
language in the Paris Agreement. For example, the inclusion of the word
must would have suggested that the content of the respective NDCs are
binding.46 Instead, Article 4(2) of the Paris Agreement provides merely
that parties ‘shall pursue domestic mitigation measures, with the aim of
achieving the objectives of such contributions’.47 While the use of the
word ‘shall’ seems to indicate an intention to be bound, this seems to
refer to ‘mitigation measures’, with the last clause ‘with the aim of
achieving the objectives of such contributions’ suggesting that it is suf-
ficient to meet this obligation if States take action aimed at the objec-
tive of the NDC, rather than a more explicit and binding obligation to
meet the requirement of the NDC.48 This interpretation is further sup-
ported by the last three words of Article 4(2), providing that each party
‘shall prepare, communicate and maintain successive nationally deter-
mined contributions that it intends to achieve’. In addition, this provision
makes it clear that there is a legally binding obligation to ‘prepare’, ‘com-
municate’ and to ‘maintain’ successive NDCs.
The use of the word ‘will’ in Article 4(3) indicates that this provision
constitutes a non- binding obligation to progressively increase each
State’s commitment to climate change mitigation, conditional on
CBDR and an assessment of the State’s ‘national circumstances’.49
Under Article 4(4), developed country parties ‘should take the lead
by undertaking economy- wide absolute emission reduction targets’.50
This suggests a soft non- binding obligation on developed country par-
ties to take the lead in mitigation reductions, and a non- binding re-
quirement to undertake economy- wide emission reduction targets.51
The provision needs to be read in conjunction with the other provi-
sions in Article 4, which make it clear that it is left up to developed
countries to decide on their own the appropriate level of mitigation
commitment in their NDC, provided that the commitment does not go
backwards in terms of ambition. Interestingly, Article 4(4) places a non-
binding obligation on developing country parties to continue enhanc-
ing their mitigation efforts (using the word ‘should’), with encouragement
that they ‘move over time towards economy- wide emission reduction
or limitation targets in the light of different national circumstances’.52
Article 4(5) indicates that there is a legal obligation to provide develop-
ing country parties with assistance for implementation of Article 4
without stating on whom this obligation rests.
The COP decision which accompanied the Paris Agreement makes
clear that there is a non- binding obligation on parties to include
particular elements in their NDCs, relating to methodology, scope and
coverage, appropriate base year and how the party considers that its
NDC ‘is fair and ambitious, in the light of its national circumstances,
and how it contributes towards achieving the objective of the
Convention as set out in its Article 2’.53
Reading these provisions together, it is clear that the Paris
Agreement does not require in a hard, binding manner a high level of
precision or ambition in terms of the content of NDCs.54 Indeed, while
developed country parties such as the EU have tended to already have
in place detailed and specific economy- wide emission reduction tar-
gets, the Paris Agreement does not make it binding to have such tar-
gets in place at all. For developing countries, the Agreement allows for
a considerable range in terms of the precision of obligations contained
within NDCs, with a non- binding obligation to move towards
economy- wide mitigation reduction targets over time. To illustrate
what this means in practice, China, in its INDC (now its NDC) submit-
ted at the end of June 2015, avoided a precise target in terms of over-
all greenhouse gas emission reductions, but rather pledged that its
carbon dioxide emissions would peak ‘around’ 2030, and that its emis-
sions per unit of gross domestic product be reduced by 60–65 percent
from 2005 levels.55
43UNFCCC ‘Decision 2/CP.15, Copenhagen Accord’ UN Doc FCCC/CP/2009/11/Add.1 (30
March 2010) para 4. However, note that the COP only ‘[took] note of’ the Copenhagen
Accord, which is less imperative than ‘shall’ or ‘agrees to’.
44UNFCCC ‘Decision 1/CP.19, Further Advancing the Durban Platform’ UN Doc FCCC/
CP/2013/10/Add.1 (31 January 2014) para 4; UNFCCC ‘Decision 1/CP.20, Lima Call for
Climate Action’ UN Doc FCCC/CP/2014/10/Add.1 (2 February 2015) para 3.
45To encourage States to pledge a fair level of greenhouse gas reductions, States were re-
quired to indicate how their INDCs would be fair; see Decision 1/CP.20 (n 44) para 14.
46UNFCCC ‘Streamlined and Consolidated Text’ UN Doc FCCC/ADP/2015/1 (11 June 2015)
para 21, option (a).
47Paris Agreement (n 1) art 4(2). The comma modifies the operative noun of ‘Parties’, requiring
them only to aim at achieving the objectives of their contributions; see Rajamani (n 6) 498.
48Rajamani (n 6) 498.
49ibid; see also Voigt and Ferreira (n 9).
50Paris Agreement (n 1) art 4(4).
51The language in Article 4(4) was changed from the imperative ‘shall’ to ‘should’, ostensibly
for the purpose of making the requirement to undertake economy- wide emission reduction
targets non- binding and appeasing the US; see S Biniaz, ‘Comma but Differentiated
Responsibilities: Punctuation and 30 Other Ways Negotiators Have Resolved Issues in the
International Climate Change Regime’ (June 2016)
files/2016/09/Biniaz-2016-06-Comma-But-Differentiated-Responsibilities.pdf> 21–22.
53See UNFCCC ‘Decision 1/CP.21, Adoption of the Paris Agreement’ UN Doc FCCC/
CP/2015/10/Add.1 (29 January 2016) para 27, which specifies that the parties agree ‘that
the information to be provided by Parties communicating their nationally determined contri-
butions, in order to facilitate clarity, transparency and understanding, may include, as appro-
priate, inter alia, quantifiable information on the reference point (including, as appropriate, a
base year), time frames and/or periods for implementation, scope and coverage, planning
processes, assumptions and methodological approaches including those for estimating and
accounting for anthropogenic greenhouse gas emissions and, as appropriate, removals, and
how the Party considers that its nationally determined contribution is fair and ambitious, in
the light of its national circumstances, and how it contributes towards achieving the objective
of the Convention as set out in its Article 2’.
54Note that parties are currently negotiating the development of ‘further guidance on fea-
tures of the NDCs’ and ‘further guidance for the information to be provided by Parties in
order to facilitate clarity, transparency and understanding of NDCs’. See UNFCCC ‘Progress
Tracker: Work Programme Resulting from the Relevant Requests Contained in Decision 1/
CP.21’ (10 April 2017)
ress_tracker_10042017.pdf> mandates 26 and 28.
55China’s first NDC can be found at:
see also Oberthür and Bodle (n 4) 53.
Partly reflecting the wide scope given to States to determine the
content of their NDCs, the combined effect of full implementation
of the NDCs would fall short of what is required to meet the
1.5/2 °C target. The UNFCCC Secretariat was given a mandate to
analyse – just prior to the conclusion of the Paris Agreement in
2015 – the combined effect of NDCs of all parties to see how these
measured up in relation to the aim of keeping global warming below
2 °C.56 In releasing this report, Christiana Figueres, the Executive
Secretary of the UNFCCC, stated that the NDCs ‘have the capabil-
ity of limiting the forecast temperature rise to around 2.7°C by
In summary, the Paris Agreement itself is undoubtedly a treaty
binding under international law, with an objective of holding average
global warming to below 1.5/2 °C and a collective non- binding ob-
jective of achieving a balance between anthropogenic emissions by
sources and removals by sinks of greenhouse gases in the second half
of the century. While in the lead- up to the Paris conference there
were calls to make NDCs binding, these calls were not heeded. The
Agreement does contain some hard, binding procedural obligations,
including a binding obligation to ‘prepare and communicate’ NDCs
and to have them inscribed on a list maintained by the UNFCCC
Secretariat. However, the substantive obligation placed on States in
relation to the fulfilment of their NDCs and their form (including the
baseline adopted) is voluntary. Both the quality and quantity (level of
ambition) of NDCs under the Paris Agreement are determined by in-
dividual countries. Developed countries are to adopt economy- wide
targets, and developing countries are encouraged over time to move
in this direction, conditional on their national capabilities. Within these
parameters, considerable scope remains in terms of the level of both
the content and precision of NDCs. Whether it matters that key sub-
stantive mitigation commitments in the Paris Agreement are only of
a soft law nature, and variable in their precision, arguably can only be
settled by carefully examining existing empirical studies in this area,
and to this we now turn.
3.1 | Comparisons between hard and soft law
Empirical studies have been undertaken to determine whether com-
pliance is more likely or not with hard compared to soft law interna-
tional obligations.58 However, the results of these studies are
inconclusive, with some examples of soft law instruments achieving
high levels of compliance and some hard law instruments low levels of
compliance.59 These studies do, however, point out that hard law in-
struments have an advantage when compared to soft law instruments
in that they require the creation of domestic laws and institutions that
can be vital points of leverage in ensuring greater compliance.60 In
addition, non- compliance with treaty- level instruments usually in-
volves greater reputational costs for States when compared to non-
compliance with soft law instruments,61 linked to the greater authority
of such norms.62
These studies, however, face acute methodological challenges, in
that it is very difficult to determine whether State compliance with
treaty obligations is because of the treaty obligation in question, or
because the State is doing what it would do anyway.63 Nevertheless, it
is significant that where States wish to ensure a change in behaviour,
treaty- level instruments with hard obligations have tended to be the
preference. Examples include the ozone agreements,64 WTO agree-
ments65 and arms control treaties.66 Arguably, the economic
transformation required to tackle climate change is more extensive
than that required by WTO agreements relating to for instance tariffs
or subsidies, which could suggest a particularly strong need for hard
obligations.67 However, if one sees the WTO agreements as the high
point of what is politically feasible, this could suggest bleak prospects
for a strong climate change regime.
A further reason why compliance tends with hard obligations to be
strong compared to soft obligations, is that compliance mechanisms
tend to be more effective when linked to precise and binding hard
obligations. However, the combination of precise and binding hard ob-
ligations does not always ensure high rates of compliance. The Kyoto
Protocol is an example of a treaty with binding and precise obligations
combined with a compliance mechanism that has not been particularly
56UNFCCC ‘Synthesis Report on the Aggregate Effect of the Intended Nationally Determined
Contributions’ UN Doc FCCC/CP/2015/7 (30 October 2015).
57UN Climate Change Newsroom, ‘Global Response to Climate Change Keeps Door Open
to 2 Degree C Temperature Limit: New UN Report Synthesizes National Climate Plans
from 146 Countries’ (30 October 2015) -
room/indc-synthesis-report-press-release/>. See further UNEP (n 16) xviii; Rogelj et al (n
58See, e.g., D Shelton (ed), Commitment and Compliance: The Role of Non-binding Norms in the
International Legal System (Oxford University Press 2003); EB Weiss and HK Jacobson (eds),
Engaging Countries, Strengthening Compliance with International Environmental Accords (MIT
Press 1998); J Pauwelyn, R Wessel and J Wouters (eds), Informal International Lawmaking
(Oxford University Press 2012).
59See generally Shelton (n 58), see also discussion of the literature in Byrnes and Lawrence
(n 3) 46–48.
60EB Weiss and HK Jacobson, ‘Assessing the Record and Designing Strategies to Engage
Countries’ in Weiss and Jacobson (n 58) 511, 536.
61G Shaffer and MA Pollack, ‘Hard vs Soft Law: Alternatives, Complements, and Antagonists
in International Governance’ (2010) 94 Minnesota Law Review 706, 718.
62J Friedrich, International Environmental ‘Soft Law’: The Functions and Limits of Nonbinding
Instruments in International Environmental Governance and Law (Springer 2013) 450.
63D Shelton, ‘Commentary and Conclusions’ in Shelton (n 58) 449, 457.
64See, e.g., Montreal Protocol on Substances that Deplete the Ozone Layer (adopted 16
September 1987, entered into force 1 January 1989) 1522 UNTS 3 (Montreal Protocol).
65See, e.g., General Agreement on Tariffs and Trade (adopted October 1947, entered into
force 1 January 1948) 55 UNTS 194; Agreement on the Application of Sanitary and
Phytosanitary Measures (adopted 15 April 1994, entered into force 1 January 1995) 1867
UNTS 493; Agreement on Trade- Related Aspects of Intellectual Property Rights (adopted
15 April 1994, entered into force 1 January 1995) 1869 UNTS 299; General Agreement on
Trade and Services (adopted 15 April 1994, entered into force 1 January 1995) 1869 UNTS
66See, e.g., Arms Trade Treaty (adopted 2 April 2013, entered into force 24 December
2014), as adopted by UNGA ‘The Arms Trade Treaty’ UN Doc A/RES/67/234 B (11 June
67We recognize that one could argue that it is precisely because the economic transformation
required is so deep – and the disagreement on how it should be achieved so profound – it may
not be advisable to use the bluntest form of international cooperation (that is, a treaty).
However, hard obligations (e.g., in the form of economy- wide binding commitment) are
possible without being overly prescriptive as to how greenhouse gas emission reductions are
to be achieved.
effective.68 Nevertheless, the effectiveness of these binding and pre-
cise obligations may be moderated by the weak sanctions in the Kyoto
Protocol.69 However, international agreements that do have effective
non- compliance procedures tend to have binding and clear obliga-
tions, such as the WTO dispute settlement system,70 the Montreal
Protocol on ozone depletion and the Convention on International
Trade in Endangered Species of Wild Fauna and Flora (CITES)71 illus-
trative of this point.
Moreover, effective compliance mechanisms require not only sup-
port in the form of capacity building to assist developing countries, but
ultimately sanctions in relation to countries where the political will to
undertake change is lacking.72 However, the Paris Agreement in Article
15 only establishes a mechanism ‘to facilitate implementation of and
[to] promote compliance’ with the Agreement, comprising a committee
to function in a ‘non- adversarial and non- punitive’ manner with details
to be decided by the COP. While the Montreal Protocol,73 CITES74 and
the WTO agreements75 all contain capacity- building mechanisms to
facilitate compliance, it is significant that all these regimes also include
sanctions in various forms. Article 15 of the Paris Agreement reflects a
lack of political will to develop a strong mechanism. Many States
seemed concerned that their sovereignty could be trammelled by a
strong compliance mechanism that could restrict their climate policy
decisions.76 In addition, developing countries could have further par-
ticular concerns that developed countries use any such mechanism –
particularly if it contained the possibility of sanctions – to adversely
impact their economic development and trade interests.77
While the voluntary non- binding nature of NDCs was arguably dic-
tated by political feasibility, some may say that this structure is in fact
optimal in allowing for the rapid scaling up of commitments over time
when compared to binding obligations as: (i) Article 4.3 imposes an
obligation on States to progressively increase their mitigation commit-
ments reflected in their NDCs; (ii) parties are subject to peer pressure
to raise ambition of their NDCs through a transparency mechanism
and a global stocktake (described below); and (iii) the delays involved
in requiring ratification of amendments that would be entailed with
hard law mitigation obligations can be avoided with the soft law oper-
ation of the mitigation commitments.
However, we disagree with this view. Turning to each of these in
turn, given the gap between current NDCs and what climate science
tells us is required, the soft obligation to not lower commitments is not
particularly helpful in terms of meeting the objectives of the Paris
Agreement. A gradual increase in mitigation commitments would
clearly be inadequate to address the imperative of climate change sci-
ence which requires deep emission reductions in greenhouse gases.78
As to the second point, peer pressure to raise mitigation ambition
would be equally possible in relation to binding commitments (i.e.,
where States are under a binding international treaty obligation to im-
plement their NDCs). In terms of the third point, the rapid scaling up of
commitments is also possible under hard law commitments. An
example of this is the Montreal Protocol on Ozone Depletion, which
uses an opt- out mechanism whereby parties that agree to particular
COP decisions involving a tighter phase- out timeline for ozone-
depleting substances, are automatically bound unless they opt out
within a certain period of time.79
3.2 | The Paris Agreement: a unique example of
treaty soft law
The assessment of effectiveness is further complicated by the fact
that the Paris Agreement constitutes a special species of ‘treaty soft
law’. Treaty soft law refers to treaties that, while binding on parties
through the operation of pacta sunt servanda,80 have terms that do not
impose enforceable obligations on parties, owing to a lack of impera-
tive language or vagueness or imprecision in the expression of the
11 December 1997, entered into force 16 February 2005) 2303 UNTS 148. The Protocol’s
compliance mechanism is analysed in J Brunnée, ‘Climate Change and Compliance and
Enforcement Processes’ in R Rayfuse and SV Scott (eds), International Law in the Era of Climate
Change (Edward Elgar 2012) 290, 311; and A Zahar, International Climate Change Law and
State Compliance (Earthscan 2015).
69J Hovi, CB Froyn and G Bang, ‘Enforcing the Kyoto Protocol: Can Punitive Consequences
Restore Compliance?’ (2007) 33 Review of International Studies 435. Some argue further that
it was a combination of the top- down approach, lack of binding commitments for developing
countries and lack of participation that led to the failure of the Kyoto Protocol; see Zahar
(n 68).
70BA Simmons, ‘Treaty Compliance and Violation’ (2010) 13 Annual Review of Political
Science 273, 285. Here we use the concept of non- compliance broadly, where it is under-
stood to include the full range of possibilities for bringing States into compliance – bearing in
mind that the WTO’s Dispute Settlement Understanding involves mandatory negotiation and
not just quasi- judicial settlement of disputes and the possibility of sanctions. However, it re-
mains unclear whether the high level of WTO compliance is linked to the binding nature of
the commitments.
71Convention on International Trade in Endangered Species of Wild Fauna and Flora (adopted
3 March 1973, entered into force 1 July 1975) 993 UNTS 243 (CITES). For an analysis of the
effective use of trade sanctions in the CITES regime, see PH Sand, ‘Sanctions in Case of Non-
compliance and State Responsibility: Pacta Sunt Servanda – or Else?’ in D Zaelke, D Kniaru and
E Kruzikova (eds), Making Law Work: Environmental Compliance and Sustainable Development
(Cameron May 2005) 259.
72We recognize that the so- called ‘managerial school’ of compliance took the view that high
levels of compliance could be achieved with little attention being given to enforcement, and
that where compliance problems existed these could be addressed through a ‘management’
approach rather than through enforcement and sanctions; see A Chayes and A Chayes, ‘On
Compliance’ (1993) 47 International Organization 175. However, other scholars pointed out
methodological flaws in the empirical studies relied on under this approach, with a tendency
to focus on treaty regimes where States were taking on obligations in relation to behaviour
which they were doing anyway. It was pointed out that regimes requiring significant be-
havioural change tended to work better when sanctions were provided for. It is this view that
we favour: see G Downs, DM Rocke and PN Barsoom, ‘Is the Good News about Compliance
Good News about Cooperation?’ (1996) 50 International Organization 379, 398; see also
Bang et al (n 15) 212, pointing out that in relation to climate change, the record of States im-
plementing commitments without international enforcement has been poor. They point spe-
cifically to the failure of States to meet their individual and collective targets agreed at the
1988 Toronto Conference.
73The Montreal Protocol (n 64) art 4, contains a ban on trade with non- parties.
74CITES (n 71) art 14.
75The WTO provides for trade sanctions in specified circumstances of non- compliance. See
Understanding on Rules and Procedures Governing the Settlement of Disputes (adopted 15
April 1994, entered into force 1 January 1995) 1869 UNTS 401 art 21–22.
76‘“Sanctions” and “Punishment” Barred from COP 21 Vocabulary’ (Euractiv 12 October
78In fact, to meet the goals of the Paris Agreement, sharp and fast reductions are necessary;
see, e.g., A Macintosh, ‘Keeping Warming within the 2 °C Limit after Copenhagen’ (2010) 38
Energy Policy 2964.
79Montreal Protocol (n 64) art 14; Vienna Convention for the Protection of the Ozone Layer
(adopted 22 March 1985, entered into force 22 September 1988) 1513 UNTS 323 art 10(2).
80Vienna Convention on the Law of Treaties (23 May 1969, entered into force 27 January
1980) 1155 UNTS 331 art 26 (VCLT).
obligations in question.81 This species of soft law has not been studied
sui generis, and to date has only indirectly been touched on in some
case studies.82 One set of these case studies – brought together by
Dinah Shelton – were selected on the basis of hypotheses about fac-
tors that might influence compliance, such as (i) the institutional set-
ting; (ii) regional diversity – impacting capacity to comply; (iii) the type
of obligation (positive or negative); and (iv) generality and specificity
of obligations.83 The impact of this type of soft law is difficult to draw
out from these empirical studies due to the range and variety of obli-
gations and the disparate goals involved in the various subject areas of
Other studies look at soft law through a different lens, for example,
through its three forms: (i) instruments created with the goal of be-
coming hard law; (ii) instruments which seek to fill gaps in existing hard
law; and (iii) instruments that seek to affect the development of both
hard and soft law.85 Treaty soft law, however, does not fit into any of
these categories and, crucially for our purposes, these studies fail to
assess the impact of ‘treaty soft law’ as a distinct category.
Nevertheless, these studies do seem to suggest that it is not the form
but the content and precision of obligations which influences, but is
not determinative of whether treaty provisions constitute obligations
likely be to be complied with. It is this indeterminacy that complicates
the assessment of efficacy within the spectrum of hard and soft law.
The obligations in the Paris Agreement in relation to the content of
the NDCs are examples of treaty soft law, precisely because while the
obligation to submit NDCs are binding obligations within a treaty, par-
ties merely resolve to ‘aim to reach global peaking of greenhouse gas
emissions’ through NDCs.86 As we saw above, while submitting NDCs
is a compulsory commitment, evinced through the use of the word
‘shall’, there is no stated commitment that parties ‘must’ achieve the
goals set out in the NDC.87 Importantly, the Paris Agreement allows a
wide variety of types of NDCs that vary in their level of precision.
Developed countries are under a non- binding obligation to adopt
economy- wide emission reduction targets and developing countries
are encouraged to adopt such targets over time. However, given the
soft nature of these obligations, both developed and developing coun-
tries can claim compliance with these provisions absent any economy-
wide emission reduction target, and merely by including, for example,
an aspirational target to reduce the amount of greenhouse gas emis-
sions per unit of energy production. For example, NDCs generally take
the form of economy- wide absolute reductions, emissions intensity
targets or how emission targets diverge from what emissions might
otherwise have been (i.e., ‘business- as- usual targets’).88 The latter are
particularly worrisome since (i) it is unclear if they constitute real emis-
sions reductions even if they are met; and (ii) countries may use differ-
ent methodologies for calculating the baseline. It remains to be seen
whether such soft, non- enforceable commitments will engender com-
pliance, similar to other treaty provisions which do not contain imme-
diate and enforceable obligations for parties, but merely codify
aspirational aims.89
While one must be careful in making generalizations from other
substantive areas of law, soft law initiatives have played a role on oc-
casion in facilitating compliance or assisting in a process of moving
towards hard law measures. Soft law has the potential to influence the
strength of binding institutions by putting pressure on slow adopters
while simultaneously giving compliant States greater negotiating
power for future agreements.90 For example, the soft law declarations
adopted by the International North Sea Conferences and legally bind-
ing norms under the Oslo and Paris (OSPAR) commissions and the EU
have sped up decision making, strengthened OSPAR and EU rules, and
improved domestic implementation of the original International North
Sea Conference declarations.91 Similarly, soft law instruments adopted
under the UN Food and Agriculture Organization have articulated the
norm that capacity- driving subsidies are undesirable, and have
strengthened the position of negotiators who favour a renegotiation
of subsidy disciplines.92
However, the Paris Agreement, while not imposing any binding
obligation on States to achieve their stated NDCs, does impose pres-
sure on laggards and non- conforming parties through its provisions
prohibiting backsliding. A further possibility is that the review provisions
of the Paris Agreement overcome the voluntary nature of each party’s
respective mitigation commitments, and to this issue we now turn.
The Paris Agreement review provisions are an extension of existing
transparency and review mechanisms established under the UNFCCC.
The UNFCCC review provisions were fleshed out in the Cancún
Agreements and are referred to as international assessment and
81See generally IA Olson, ‘Four Competing Approaches to International Soft Law’ (2013) 58
Scandinavian Studies in Law 177, 180–184.
82But see the analysis of the Convention on Biological Diversity through this lens: SR Harrop
and DJ Pritchard, ‘A Hard Instrument Goes Soft: The Implications of the Convention on
Biological Diversity’s Current Trajectory’ (2011) 21 Global Environmental Change 474.
83D Shelton, ‘Introduction: Law, Non- law and the Problem of Soft Law’ in Shelton (n 58) 1,
84For example, in Shelton (n 58), particular case studies of soft law instruments were compiled
in relation to these four factors from the realms of human rights, environmental protection,
arms control, and trade and finance.
85AK Bjorklund, ‘Assessing the Effectiveness of Soft Law Instruments in International
Investment Law’ in AK Bjorklund and A Reinisch (eds), International Investment Law and Soft
Law (Edward Elgar 2012) 51, 65.
86Paris Agreement (n 1) art 4(1)–(3).
88For an estimate of how these voluntary targets would impact climate change, see UNEP (n
16). Note also that the soft form of these targets contributes to both instrumental and sys-
temic uncertainties that negatively affect compliance; see J Watson, R Gross and I
Ketsopoulou, ‘The Impact of Uncertainties on the UK’s Medium- Term Climate Change
Targets’ (2015) 87 Energy Policy 685.
89Examples include the 1961 European Social Charter, the 1966 United Nations Covenant on
Economic, Social and Cultural Rights and, in the environmental context, the 1992 Convention
on Biological Diversity. Note in this article we use the term ‘compliance’ to also cover soft law
90JB Skjærseth, OS Stokke and J Wettestad, ‘Soft Law, Hard Law, and Effective Implementation
of International Environmental Norms’ (2006) 6 Global Environmental Politics 104, 115.
91ibid 106.
92ibid 112.
review for developed countries and international consultation and
analysis for developing countries.93 Under these mechanisms, States
submit biennial reports that may be are subject to a technical expert
review as well as analysis and review by other parties, allowing – in
theory – for the public discussion of compliance and adequacy of miti-
gation commitments. The Paris Agreement explicitly retains the utility
of these mechanisms as a baseline for the future meeting of parties to
the Paris Agreement to flesh out appropriate common modalities, pro-
cedures and guidelines for transparency.94 Importantly, these review
mechanisms impose common obligations on all parties.
In the Paris Agreement, the review provisions are:
(i) Article 13, which establishes an enhanced transparency
framework which takes into account Parties’ different
(ii) Article 14, which establishes a global stocktake assessing the
‘the collective progress towards achieving the purpose of this
Agreement and its long-term goals’ which is to occur every
five years, and be assessed ‘in the light of equity and the best
available science’.96
(iii) Article 15, which establishes a mechanism to facilitate imple-
mentation of – and promote compliance with – the Paris
Agreement. This mechanism consists of an expert-based facil-
itative committee which will report annually to the COP.97
Concerning the first point, transparency provisions have the po-
tential to engender compliance through reputational costs, an effect
which is particularly strong where the commitment is in treaty form,
as opposed to a mere political commitment.98 Bodansky has sug-
gested that the transparency and accountability mechanisms of the
Paris Agreement could achieve the same result as binding obligations
in that it is more likely that ‘poor performance will be detected and
criticized’, thus raising the ‘reputational costs of failing to achieve
one’s NDC’.99 However, the procedures according to which the trans-
parency framework will operate under the Paris Agreement, remain
to be developed.100 Moreover, we dispute that such mechanisms can
in themselves make up for a lack of binding commitments.
Concerning the second point, while the ‘global stocktake’ provision
is welcome, it remains to be seen how effective this process will be.
Uncertainty remains, both in terms of what the ‘long- term’ goals are
and the scope of ‘equity’ in relation to the stocktake.101 Moreover,
given the collective nature of this provision, it is unlikely to be particu-
larly effective in placing pressure on individual countries to increase
their NDCs.102
Regarding the third point, the implementation and compliance
committee established pursuant to Article 15, is to be ‘non- adversarial’
and ‘non- punitive’ and ‘respectful of national sovereignty’.103 Crucially,
the committee lacks compulsion other than through the potential
reputational costs arising from its reports.104 In addition, the Paris
Agreement is silent on providing third parties the right to ask ques-
tions relating to compliance.105 Van Asselt points out that while there
are positive examples from other regimes in terms of enhancing com-
pliance performance by involving nongovernmental organizations in
non- compliance procedures, the language of the Paris Agreement
provision referring to non- compliance ‘seemingly offers ammunition
for parties not willing to subject themselves to scrutiny by non- state
actors’.106 This is worrying because, absent NGO participation, the
provisions will not be able to ensure pressure on compliance is
enhanced to information which links to States’ reputations. Studies
have shown that non- compliance can be minimized if States suffer
high reputational costs for non- compliance.107
In summary, it is our view that these provisions cannot in them-
selves make up for the lack of binding mitigation commitments else-
where in the Agreement.108
If one accepts the argument of this article that hard (binding) mitiga-
tion commitments are more likely to be complied with, the question
arises whether the existing obligations in the Paris Agreement could
be made binding over time in conjunction with appropriately ambi-
tious NDC commitments in order to make the Agreement more
effective.110 Space constraints preclude a full analysis of the range of
options available. Our analysis focuses on two options that involve
93Decision 1/CP.16 (n 25) paras 46(d) and 63. Note that early versions of these provisions
were already in existence prior to Cancún, see H van Asselt, H Sælen and P Pauw, ‘Assessment
and Review under a 2015 Climate Change Agreement’ (Nordic Council of Ministers 2015).
94Paris Agreement (n 1) art 13(3)–(4).
96ibid art 14.
97ibid art 15.
98Bodansky (n 34).
100The negotiation of modalities, procedures and guidelines as to how the mechanism will
operate continues to be negotiated, with no solid progress; see UNFCCC (n 54).
101As distinct from the purpose of the Agreement in Article 2 to meet the 2 °C/1.5 °C goal.
Note that while there are qualitative goals related to mitigation and adaptation, goals in rela-
tion to finance, capacity building and technology are absent; see further Rajamani (n 6) 504.
103Paris Agreement (n 1) art 15(2).
104Procedures for the non- compliance committee created under Article 15 of the Paris
Agreement are still being negotiated and, therefore, the precise scope of the committee is not
yet determined; see UNFCCC (n 54) mandate 103.
105Third- party non- State actors play an important role in assessing criteria absent from the
formal processes, free from the political constraints of intergovernmental processes; see H
van Asselt, ‘The Role of Non- State Actors in Reviewing Ambition, Implementation, and
Compliance under the Paris Agreement’ (2016) 6 Climate Law 91, 106.
106ibid 103.
107See, e.g., BA Simmons, ‘Compliance with International Agreements’ (1998) 1 Annual
Review of Political Science 75, 81.
108While not addressed here, implementation of mitigation commitments is – particularly for
developing countries – a question of capacity building and financial resources. A recent study
estimated that the costs faced by developing countries in implementing their NDCs could
amount to more than US$4 trillion; see J Vidal, ‘Poor Countries Must Find $4tn by 2030 to
Avert Catastrophe, Says Climate Study’ (The Guardian 22 April 2016).
109This section draws on Byrnes and Lawrence (n 3) 63–65.
110Though we recognize the potential danger this process has in making the NDCs less ambi-
tious or that parties who fail to implement their NDCs might withdraw from the Agreement
rather than remain a party and suffer the costs of punitive sanctions for non- compliance; see
Bang et al (n 15) 214.
building upon obligations already present in the Paris Agreement,
namely: (i) a COP decision rendering the substantive obligations con-
tained within each party’s NDC submitted under Article 4 of the
Agreement legally binding; and (ii) a declaration by States committing
themselves to implement their NDCs as an international legal obliga-
tion between themselves. As noted above, an amendment to the Paris
Agreement is technically an option, but unlikely to be politically
5.1 | A decision by the Conference of the Parties
A COP decision could be passed embodying an agreement that the
Article 4 obligation relating to NDCs was to be considered legally
binding. In light of Article 41 of the Vienna Convention on the Law of
Treaties, which allows for parties to a treaty to modify treaty obliga-
tions amongst themselves, such a course is clearly technically
possible.111 If such a COP decision was agreed upon, then it would
only be operative in relation to those States who agreed to be bound
by the decision.112 This option is complicated by the failure by parties
to date to reach agreement on rule 42 of the Rules of Procedure
which specifies that, if a consensus cannot be reached in relation to a
matter of substance, then a decision can as a last resort be taken by
a two- thirds majority of the parties present and voting.113 In practice,
parties have generally adopted all decisions by consensus. The
ongoing impasse in relation to this rule makes it uncertain what
majority would apply in relation to a COP decision of the nature con-
sidered here. From the point of view of political feasibility, it would
seem unlikely in the near future that there would be sufficient
support in relation to such a decision, for either a two- thirds majority
vote, let alone a consensus.
5.2 | A declaration by States
A declaration would allow the States supporting the hard law option
to treat Article 4 of the Paris Agreement amongst themselves as creat-
ing a legally binding obligation on each of them to implement their
NDCs. Such a declaration could be worded to make it clear that it is a
subsequent agreement falling within the scope of Article 41 of the
Vienna Convention on the Law of Treaties. While technically possible,
such a declaration would likely only be entered into by those States
who already had strong climate mitigation policies in place and those
States who during the negotiations leading up to Paris expressed sup-
port for binding mitigation commitments within a binding treaty. This
would most likely include the Alliance of Small Island States, the least
developed countries, the Environmental Integrity Group114 and the
While building support for such a declaration would clearly be
challenging, such a project – also focusing on the substance of parties’
mitigation commitments – could help build momentum on this issue,
particularly if it was also taken up by a broad range of nongovernmen-
tal organizations from both the North and the South.
There is no doubt that the shift away from binding targets and
timetables epitomized in the Kyoto Protocol towards the ‘bottom- up’
architecture of the Paris Agreement facilitated consensus in Paris.
Strong leadership from the French and other key governments in the
negotiation process made this consensus possible. The incorporation
of soft, non- binding commitments in the Paris Agreement was an
essential element in this consensus, and is in that sense a ‘strength of
the agreement’. As we have seen, the Paris Agreement provides in rela-
tion to all parties that their NDCs be voluntary and are housed outside
the Agreement. In relation to these key mitigation commitments, the
main binding hard obligations are procedural – in terms of submitting
and updating of NDCs – and related to transparency, with the latter
provisions still being fleshed out by parties. The soft, non- binding na-
ture of the key commitment relating to the implementation of NDCs
enabled agreement in Paris, as it allowed the negotiators to sidestep
the thorny issue of whether developed as opposed to developing
countries would need to take on a different quality and stringency of
commitments. This was welcomed by the US and a range of developed
countries that wished to move beyond the bifurcated commitments
structure represented in the UNFCCC Annexes and the Kyoto Protocol.
It was also welcomed by China and India and many developing coun-
tries anxious that no constraints be placed on their economic develop-
ment. However, the justice concerns underlying the burden- sharing
debates which have plagued the climate negotiations for decades will
not disappear, but will rather take on a different form (with, for exam-
ple, parties framing their NDCs taking into account what they perceive
to be fair, including in relation to action taken by other countries).116
The use of soft law in key provisions of the Paris Agreement relating
to mitigation raises serious concerns in terms of its effectiveness and is,
in this sense, a potential weakness of the Agreement. As stated at the
outset of this article, the effectiveness of environmental treaties is a
111VCLT (n 80) art 41 reads: ‘Two or more of the parties to a multilateral treaty may conclude
an agreement to modify the treaty as between themselves alone.’ A precondition of this is
that this modification does not affect other parties’ rights and obligations under the particular
treaty (ibid art 41(1)(b)), which would appear to be met in this circumstance.
112UNFCCC ‘Draft Rules of Procedure of the Conference of the Parties and its Subsidiary
Bodies’ UN Doc FCCC/CP/1996/2 (22 May 1996).
113Legal Response Initiative, ‘Procedural Rules of the Climate Negotiations’ (Legal Response
Initiative 2013)
UNFCCC-process.pdf> 3. See also UNFCCC ‘Report of the Conference of the Parties on its
Twenty- First Session, Held in Paris from 30 November to 13 December 2015’ UN Doc
FCCC/CP/2015/10 (29 January 2016) 6.
114The Environmental Integrity Group comprises Mexico, Liechtenstein, Monaco, the
Republic of Korea and Switzerland. This is a negotiating group that represents the shared in-
terests of the aforementioned States at the UNFCCC.
115Byrnes and Lawrence (n 3) 43. The authors would like to thank Jonathan Pickering for the
idea of a declaration binding between States. The idea was adapted from B Müller, W Geldhof
and T Ruys, ‘Unilateral Declarations: The Missing Legal Link in the Bali Action Plan’ (European
Capacity Building Initiative 2010)
116For an analysis of the interaction between issues of hard versus soft law and notions of
justice in relation to the climate negotiations, see Byrnes and Lawrence (n 3); and P Lawrence,
‘Justice and Choice of Legal Instrument under the Durban Mandate: Ideal and Not So Ideal
Legal Form’ in D Roser and C Heyward (eds), Climate Justice in a Non-ideal World (Oxford
University Press 2016) 125.
combination of participation, quality and stringency of commitments,
and implementation. While soft commitments facilitated widespread
participation in the Paris Agreement, serious concerns remain as to the strin-
gency and voluntary nature of commitments contained in the Agreement
in terms of meeting the overarching goals of the Paris Agreement.
We have seen that empirical research comparing the relative
levels of compliance in relation to hard and soft instruments and
obligations are equivocal. Nevertheless, binding and precise ob-
ligations in treaty- level instruments clearly have an advantage in
that they require domestic constitutional processes, including, for
example, legislation passed through parliaments in parliamentary
democracies, which can provide an essential leverage point for im-
plementation. Moreover, when governments have strong political
will to change behaviour, then more often than not, hard law treaties
are used with hard and precise commitments, combined with strong
mechanisms to address non- compliance or settle disputes (as in the
case of the Montreal Protocol, CITES and the WTO agreements). As
we have seen, the Paris Agreement does not prescribe any conse-
quences for parties failing to achieve the goals set out in any NDCs,
it allows for NDCs that may be lacking in precision in terms of the
commitment involved, and it has only weak provisions for a non-
compliance mechanism. All of these elements create serious risks in
terms of the likely effectiveness of the Paris Agreement. While the
transparency and other review provisions of the Paris Agreement
are welcome and should be made as effective as possible, these pro-
visions in themselves cannot be a substitute for hard and precise ob-
ligations, an effective compliance mechanism, and – above all – the
political will to reduce emissions. All of these elements remain key
requirements for the effectiveness of this agreement.
Absent research unequivocally demonstrating that strong compli-
ance is possible with treaty soft law environment agreements, the
Paris Agreement represents a gamble – taking a punt on ‘voluntary
international law’.117 Indeed, the Agreement can be said to represent a
gamble with future generations and the global ecological system due
to the serious risks involved in delaying strong action on climate
change, owing to resultant lock- in of fossil- fuel- based technologies.118
While current constraints related to policies of the Trump
Administration in the US, the present make- up of the US Congress,119
geopolitics, vested economic interests, the limitations of the multilat-
eral negotiation process and other factors may explain this gamble, it
is nevertheless important to see the Paris Agreement for what it is.
This is not to deny that various elements of the Paris Agreement
may be taken up by non- State actors and institutions and used to fur-
ther the transition to a carbon- neutral global economy. In this article,
we have argued that in addition to these strategies, efforts should be
made to garner political support for converting the currently non-
binding obligations120 in the Paris Agreement relating to the substance
of the NDCs into binding mandatory obligations. We have seen that
the options of either a COP decision or political declaration are both
technically possible. However, a COP decision would have the addi-
tional complication relating to the ongoing uncertainties about the
rules of procedure. From this perspective, upgrading NDC commit-
ments from soft to hard obligations through a declaration would seem
to be potentially more realistic. A declaration would have the attrac-
tion that this could be an initiative pursued by those governments will-
ing to take a stronger leadership role, without negatively impacting
ongoing work in other areas of the negotiation agenda. To be effective,
such a strategy would need to address the level of ambition and preci-
sion of NDCs, but also the need to build a strong compliance mecha-
nism (which is likely to be an uphill battle given the Paris Agreement
language). It would also need to address other important issues related
to implementation which have not been canvassed in this article, in-
cluding, finance, technology development and transfer and capacity
building. Nevertheless, given the enormous diplomatic capital ex-
pended in negotiating the Paris Agreement, it would be difficult at the
present time to persuade governments to commence negotiations in
this direction. While the political context remains challenging, steps in
this direction must be taken to ensure that the Paris Agreement meets
its objectives.
How to cite this article: Lawrence P, Wong D. Soft law in the
Paris Climate Agreement: Strength or weakness? RECIEL.
117R Falk, ‘“Voluntary” International Law and the Paris Agreement’ (17 January 2016)
118See, e.g., International Energy Agency (IEA), Energy and Climate Change, World Energy
Outlook, Special Report (IEA 2015) 134.
119Including the subsequent movements of the US, given President Trump’s announcement
that the US would withdraw from the Paris Agreement; see ‘Full Transcript: Trump’s Paris
Climate Agreement Announcement’ (CBS News 5 June 2017)
news/trump-paris-climate-agreement-withdrawal-announcement-full-transcript/>. 120See, e.g., Paris Agreement (n 1) art 4.
Peter Lawrence is a Senior Lecturer at the University of Tasmania
Law School, teaching international law and supervising the
University of Tasmania Law Review. Peter researches in the field
of climate change, justice and ethics and is author of Justice for
Future Generations, Climate Change and International Law (Edward
Elgar, 2014). In 2016, Peter was a visiting research scholar at the
University of Utrecht Ethics Institute. He is currently working on a
Germany (DAAD)–Australia joint research project on the represen-
tation of future generations through international climate litigation.
Previously, Peter worked as a diplomat and was First Secretary for
the Australian Permanent Mission to the United Nations in Geneva
Daryl Wong holds a Bachelor of Laws (First Class Honours) from
the University of Tasmania Law School and is a former editor of the
University of Tasmania Law Review. Daryl is currently working as a
trainee barrister and solicitor at the firm Wong Partnership LLP in

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