These are fraught times for global treaty-making. Geopolitical tensions, populist impulses, powerful economic forces, and scientific and technological uncertainty vastly complicate negotiations. In 2022, the UN secretary-general complained that multilateralism was under attack, and things have only worsened since then. Despite this, three multilateral treaties have been adopted by consensus in the last two years: the Agreement on Marine Biodiversity of Areas beyond National Jurisdiction (2023), the UN Convention against Cybercrime (2024), and, after the US delegation withdrew, the Pandemic Agreement (2025). The Pact for the Future—not a treaty but a global normative instrument—was also adopted by consensus in September 2024. Negotiations are underway on multilateral treaties on tax cooperation and crimes against humanity. So, while the headwinds are against successful treaty negotiations, it is premature to declare the death of multilateralism.

An important test case in the coming month is the effort to end plastics pollution. Negotiations on a global plastics treaty were mandated by the UN Environment Assembly in March 2022. The negotiating mandate is broad (“a comprehensive approach that addresses the full life cycle of plastic”), and the battle lines quickly formed between those who support a strong treaty and those who oppose it. About 99% of plastics are currently fossil fuel–derived, though bioplastics hold significant sustainable potential. Plastics are both a source of health-damaging pollution and essential to the built world (we wear, sit in, work in, sleep in, eat out of, and increasingly drive and fly in plastics). There are deep vested interests and strongly held beliefs among major governments, industries (especially the petrochemical industry), major brands (from apparel to food), scientists, and those who represent both impacted communities and ecosystems along the lifecycle of plastics (such as “plastic pickers” associations).

The negotiations were meant to conclude in December 2024, but the session was extended to August 2025. Several thorny issues are yet to be resolved. Will the treaty set a global target to reduce plastics production? Will it yield agreement on “upstream” or “midstream” problems like banning single-use plastic products and hazardous chemicals? Or will it focus only on the downstream: plastic recycling and waste management? What sort of financing mechanism will be put in place, and where will the resources come from? Questions also remain about underlying principles, subsidiary bodies to be established, and the voting rules for amendments and annexes to the treaty.

Progress was made at the December 2024 session of the International Negotiating Committee (INC-5.1), and there is still hope for a substantively strong treaty, but there is no guarantee of success at the second round of the fifth session this August in Geneva (INC-5.2). The political dynamics have also changed since December with the start of the second Trump administration, which announced it would support an agreement that focuses on “reducing plastic pollution, not on stopping the use of plastics.”

As with many other treaties, even if it is possible to reach agreement on a strong initial plastics agreement, the level of scientific, technical, economic—and political—uncertainty means that procedural and institutional mechanisms must be baked into the original text to allow for adaptation and further strengthening over time. Treaty-making in the face of uncertainty is best conceived as an extended regime-building exercise, not as a one-off process that ends when a treaty comes into force. Even when they begin with strong core obligations, most multilateral agreements must be treated as dynamic works-in-progress.

It is therefore important to think about treaty “strength” along two axes: substantive and procedural. Negotiating vigorously for a range of substantive core obligations is, of course, important. No amount of subsequent strengthening can make up for an anemic start. But whatever its core obligations, the plastics treaty will benefit from a resilient process and coherent structure that facilitate ongoing interaction and negotiation and the raising of standards and ambition over time—what might be called good “process bones.”

There are five interrelated mechanisms that could provide a strong structure and process for addressing plastics pollution, regardless of the treaty’s level of obligations on day one: (1) regular national reporting by the parties; (2) an expert scientific input function; (3) an implementation and compliance committee; (4) a conference of the parties (COP) that makes decisions by majority vote; and (5) a defined process to amend, upgrade, or add substantive obligations. Details about these mechanisms should be included in the agreement itself rather than kicked down the road to the COP.

A National Reporting Mechanism

Regular reporting by the parties is a critical building block of treaty implementation and an indicator of treaty health. It encourages domestic and international transparency and thereby enhances the prospects for compliance. It also builds national capacity: governments must initiate domestic processes, self-monitor, engage industry, and collect data. Such reporting can take two forms: (1) “operational” (normally on an annual basis), focused on implementation of the core substantive obligations of the treaty, with measurable statistical data provided under specified headings; and (2) “reflective” (every two to five years), focused on the effectiveness of implementation, including impacts, challenges, and domestic regulation. There have been calls for both kinds of reports for the plastics treaty.

The most recent draft of the treaty (embodied in the Chair’s Text of December 2024) takes a middle path, providing for regular national reports on the implementation of national plans (draft Article 14). The secretariat will make national plans and reports publicly available and regularly inform the COP of countries that have not submitted their reports. The format and periodicity of the reports are left to the COP. Whether the reports are meaningful will depend on the final agreed scope of the national plans (i.e., the “actions and measures” the parties take to implement the treaty). These plans are to be updated and enhanced based on (so far unspecified) guidelines and to draw on consultations with national stakeholders.

There is scope for strengthening the final language on national reporting once negotiators have agreed on core obligations in other articles.

Institutionalized Scientific and Technical Input

An unusual breadth of scientific issues arises throughout the lifecycle of plastics—from the chemicals that go into plastics to the impact of “legacy” fishing nets on reefs and of airborne nanoplastics on humans. To succeed, the treaty will thus need sustained scientific input from a broad range of experts.

The current draft bifurcates the issue of technical input between two articles. Draft Article 3 on plastic products, which is heavily bracketed (i.e., disputed), mandates the COP to create a Review Committee to look at single-use and other problematic products, but not all the bracketed options would ground the “review” in a robust scientific framework. Draft Article 20 simply mandates the first COP to establish “a subsidiary body or bodies to provide scientific and technical information and assessment to support informed decision-making” with no details about terms of reference, composition, or organization. The risk is a weakened Article 3 that does not provide for a robust scientific review process and a watered-down Article 20 that essentially kicks the issue down the road to the COP.

To ensure sustained scientific input, the text of the treaty should clearly delineate two or more scientific subsidiary bodies: one to drive the review of national reports or other periodic evaluations, and one to carry out the scientific and technical assessment of plastic products and polymers/chemicals of concern. The treaty text should specify the core mandates of the committees and their composition by independent experts (rather than government representatives).

An Implementation and Compliance Committee

In a step forward from earlier drafts, Article 13 of the December 2024 text calls for establishing a “mechanism, including a Committee” to “facilitate the implementation of and promote compliance with” the provisions of the treaty. It specifies that the committee will operate on a “transparent, facilitative, non-punitive, non-adversarial basis.” Achieving an acceptable level of compliance with a treaty does not always require punitive measures or even robust dispute settlement procedures. Softer, facilitative, or non-adversarial approaches can be effective, especially if they translate into reputational costs for noncompliance. A committee to oversee such measures can both help the parties meet their commitments and pressure them to do so when necessary.

Nevertheless, Article 13 has three weaknesses. First, it does not specify whether the committee will be composed of independent experts (third-party review) or by the parties themselves (peer review). The treaty should specify the former—a committee composed of nongovernmental experts who are nominated and elected by the parties. Second, it is silent about whether the committee can rely on information provided by sources other than governments. Such nongovernmental sources should be explicitly allowed. Third, the committee’s modalities and rules of procedure are left to the COP. Ideally, the treaty should specify the committee’s functions, including receiving national reports, engaging in constructive dialogue with the parties, sharing best practices, and engaging in gentle “naming and shaming”as needed to promote compliance. It should also specify a  decision-making procedure that allows for a three-quarters majority vote if it is not possible to reach consensus in the committee.

Review by the Conference of the Parties

The effective functioning of any treaty regime depends heavily on the powers given to the main governing body, typically a COP. For the plastics agreement, several functions of the COP proposed in the current draft stand out. It can establish subsidiary bodies; it can cooperate with other international organizations; it reviews and adopts decisions related to implementation; and it undertakes any other functions necessary for implementation. In draft Article 16, it is empowered to evaluate the effectiveness of the treaty on a regular basis, starting six years after it comes into force. A positive feature of these evaluations is that they will be based not only on the national reports but also on information provided by the implementation and compliance committee and any other information it deems relevant—including scientific and technical assessments.

However, given the difficult history of the consensus rule in the plastics treaty negotiations to date, it is concerning that the draft text specifies that the parties must agree by consensus on the COP’s rules of procedure and those of all subsidiary bodies at its first meeting. This can lead to paralysis. It would be preferable for the treaty to specify at the outset the voting threshold for the COP’s substantive decisions (three-quarters majority) and procedural decisions (simple majority).

A Formal Process to Upgrade Core Obligations

If, as suggested above, a treaty should be understood as a work-in-progress, then it requires formal arrangements to adapt and, if necessary, upgrade its substantive terms. Upgrading can include: (1) ratcheting up ambition on existing obligations, (2) converting nonbinding provisions into binding obligations, and (3) adding specificity (e.g., specific targets). Revisions can take the form of amendments to the treaty text and its original annexes or the addition of new annexes and protocols. The revision process can be triggered through review conferences or “stocktakes,” either on specified dates or when requested by a simple or qualified majority of the parties. There are several alternatives for who is bound by these revisions (all parties, only parties that ratify or accede to the amendment, or all parties unless they “opt out”) and when.

The current draft includes, in square brackets, the possibility of adopting amendments by three-quarters majority vote. It includes similar provisions for amending existing annexes or adopting new ones  (though new annexes are restricted to procedural, scientific, technical, or administrative questions). This voting threshold is appropriate and must be retained. To mitigate concerns that such changes to the original treaty could infringe on state sovereignty, the treaty could specify that amendments will be binding only on states that ratify them, and annexes only on states that choose not to opt out.

Conclusion

To remain effective over time, multilateral treaties should be thought of as dynamic, long-term arrangements that seek to structure relationships among multiple parties and associated non-state actors. These relationships can create an institutional and normative environment—a “relational infrastructure”—that facilitates movement toward a stronger treaty. Together, the five mechanisms suggested here can stimulate that movement. Each has been discussed in the negotiations on the plastics pollution treaty, but their fate remains uncertain in the final push.

Ian Johnstone is a Professor of International Law at the Fletcher School at Tufts University. Joshua Lincoln is a Senior Fellow (non-residential) at the Centre for International Law and Governance at the Fletcher School.