David Collins | September 13, 2026
UK-EU Reset
Key aspects of the United Kingdom’s (UK) international trade commitments are incompatible with its ongoing objective of pursuing closer ties to the European Union (EU). This process, known colloquially as the “reset,” refers to the attempted reversal of the period of regulatory divergence associated with the UK’s separation from the EU which had been achieved under the previous Conservative government. The anticipated dynamic alignment with the EU on agrifoods and emissions trading runs the risk of violating international law, most notably the terms of the 12-nation Comprehensive Progressive Trans-Pacific Partnership (CPTPP) as well as the World Trade Organization’s (WTO) General Agreement on Tariffs and Trade (GATT). Post-Brexit re-alignment with the EU accordingly exposes the UK to retaliation from its other trade parties and could frustrate future bilateral trade negotiations with partners such as the United States (US).
It has been six years since the UK’s formal departure from the EU in early 2020 following the 2016 “Brexit” referendum, and the subsequent ratification of the Trade and Cooperation Agreement (TCA), a preferential trade agreement. The current Labour government in the UK now seeks closer regulatory ties to the 27-member economic and political union, which remains its largest trading partner. There is currently a set of proposed UK–EU agreements, alongside an expected piece of UK implementing legislation that would give the agreements legal effect domestically.
Within that framework, two specific agreements are being negotiated, both of which raise problems for the UK under international law. The first is a proposed sanitary and phytosanitary (SPS) agreement covering rules on food safety, animal health, and plant health. The aim of this accord is to reduce or remove border checks on agricultural and food products by creating a common SPS area between the entirety of the UK and the EU. Northern Ireland is already aligned with the EU in this area under the terms of the TCA’s Northern Ireland Protocol. In order to achieve this, the UK would commit to keeping its rules in alignment with EU law on an ongoing basis—known as “dynamic alignment.” This means that when EU rules concerning the SPS agreement change, the UK would update its own rules correspondingly within the scope of the agreement.
The second agreement currently being negotiated is a proposal to link the UK emissions trading system with the EU’s carbon emissions trading system. The UK already operates its own carbon market but linking it to the EU system would permit allowances to be traded across both systems. For such a link to function, both sides need broadly consistent rules. As a result, this agreement would also involve a commitment by the UK to maintain alignment with relevant EU rules over time in the areas covered by the linkage. This will require the UK to adopt the EU’s new carbon-border adjustment mechanism (CBAM) through which tariffs are imposed on imported goods in a manner that reflects the carbon intensity of their production.
SPS
Unfortunately, however, EU alignment with SPS (essentially agrifoods) could undermine the UK’s commitments under the CPTPP which it joined as the newest member in 2025. A key area of conflict relates to the CPTPP’s emphasis on risk-based measures, which is set out in Article 7.9. This provision states that measures that do not conform to international standards must be “based on documented and objective scientific evidence that is rationally related to the measure.” The possible incompatibility with EU SPS rules arises due to the EU’s application of the Precautionary Principle, which allows it to adopt SPS measures even in the absence of full scientific certainty if there is a potential risk. This principle is embedded in EU law, and informs EU policy on imports of foods, feed, and agricultural products. For example, the EU still bans hormone treated beef, despite the fact that this practice was found to be not scientifically justified by the WTO Appellate Body. Under the CPTPP approach, such precautionary measures might be viewed as “unjustified” or “arbitrary” if the UK cannot provide a full quantitative risk assessment that satisfies the CPTPP standard.
If a complaint was successfully brought against the UK under the CPTPP’s dispute settlement process (set out in Chapter 28) by another CPTPP signatory, alleging breach of the SPS chapter because the UK followed “unscientific” EU rules, the UK would not be able to comply with the panel ruling. In order to comply, it would need to negotiate an exemption from Brussels, which would almost certainly not be forthcoming. Moreover, since virtually all free trade agreements (FTA) have SPS chapters, many of which contain similar provisions to the CPTPP (e.g., UK-Australia, UK-New Zealand), it is difficult to see how the UK will be able to sign any FTAs in the future as it would no longer be in control of its SPS policy. Alignment with EU SPS regulation would almost certainly have a negative impact on any future trade relationship between the UK and US.
Carbon Emissions Trading
In relation to emissions trading, linking the UK system to the EU ETS would necessitate alignment with EU’s soon-to-be implemented CBAM, as noted above. Issues could arise if the UK, by mirroring the EU CBAM, imposes additional carbon-related costs on imports from CPTPP countries. Those partners could claim that this amounts to discrimination or an unnecessary obstacle to trade, especially if the CBAM methodology does not adequately recognize different production methods or equivalent climate policies in exporting countries. Perhaps even more problematically, it is doubtful that CBAM is compliant with GATT Article II, which prohibits tariff increases beyond bound levels, and GATT Article I, which prohibits discrimination based on origin. It might be argued that the CBAM, as an environmental policy, may be justified under the GATT’s General Exceptions, notably Article XX(g) “measures relating to the conservation of exhaustible natural resources” which might, if stretched, cover the climate system, or Article XX(b) “human, animal or plant life or health” although these are not the primary objectives of the CBAM. The test for GATT XX is a very strict one, in particular because of the “chapeau” of Article XX, which requires that the measure must not constitute “arbitrary or unjustifiable discrimination” or a “disguised restriction on international trade.” GATT caselaw has shown this to be a difficult test to pass. The UK or EU would need to demonstrate that the application of the CBAM, including its treatment of developing countries, embedded emissions methodologies, or recognition of equivalent foreign climate policies, was conducted even-handedly. Certainly, the UK should expect complaints from other WTO members.
Conclusion
The CPTPP, GATT and other FTAs were based on the premise that parties largely retain the freedom to set their own regulations provided that they do not create undue trade barriers. Alignment with EU SPS and emissions trading rules—particularly if dynamic—would appear to reduce the UK’s ability to adjust its rules in ways that facilitate trade with CPTPP and other treaty partners, including the broader WTO membership. This could undermine the UK’s ability to deliver the market access or regulatory cooperation benefits that international trade law, embodied by trade treaties, was crafted to achieve. It is also worth noting that the EU comprises an ever-decreasing component of global GDP, and some studies have shown that the adoption of EU SPS regulations could end up costing the UK economy billions of pounds per year due to regulatory inefficiencies.
Most importantly for international lawyers, dynamic alignment with the EU represents a prioritization of economic relations with the EU over those of the UK’s other trade partners, and, in so doing, places elements of the UK’s existing trade obligations, including those undertaken as a member of the WTO, in jeopardy. These actions send a worrisome message to the global community that the UK does not respect international law’s foundational principle of pacta sunt servanda (“agreements must be kept”—codified in Article 26 of the Vienna Convention) and, perhaps worse, could indicate that the UK is an unreliable trading partner.
David Collins is a Professor of International Economic Law at City St George’s, University of London.