The United Kingdom has long been a strong supporter of international environmental law and is currently party to more than 40 international treaties, covering areas such as climate change, the transfrontier movement of hazardous wastes and preservation of internationally important nature protection sites. While the UK government has stated that it is committed to upholding the United Kingdom’s international obligations post-Brexit, that nation’s departure from the European Union raises important and complex legal issues concerning exactly which international environmental treaties remain binding. The problem is rooted in the European Union’s own involvement in many environmental treaties.

There are a small number of treaties where the European Union has been excluded because it lacks legal competence in the area — the international Whaling Convention, for example. These will continue to bind the United Kingdom post-Brexit. In some areas, as a matter of EU law and largely as a result of case law of the European Court of Justice, the European Union is considered to have exclusive competence and has ratified treaties on its own, thereby binding all EU member states. In this case, the United Kingdom will not be bound, unless it makes a conscious decision to sign and ratify independently.

But the vast majority of international environmental treaties are so-called “mixed agreements” in which the subject matter straddles the legal competences of both the European Union and its member states. In such cases, both the Union and its member states have ratified. Often, the division of competences is deliberately not defined precisely, much to the frustration of third countries.

This is where legal issues have been raised as to what happens after Brexit. Legal opinions differ. Some have argued that the mixed agreements will also fall unless the United Kingdom decides to ratify the treaties in question. Others believe that upon departure from the European Union, the United Kingdom will acquire all the competences previously held by the Union and will continue to be bound as a matter of international law. Both scenarios fall into uncharted legal waters.

Until now, government statements that the United Kingdom will continue to be bound by its international commitments have been ambiguous. It would be helpful for the international community, UK parliamentarians and members of the public for the government to publish its definitive legal understanding of the post-Brexit position, especially in relation to mixed environmental agreements. In an ideal world, the United Kingdom and the European Commission would issue a joint statement — assuming they are agreed — since it is in both their interests that the international environmental legal order is not compromised by Brexit.

Even if these problems are worked out, and the United Kingdom remains bound by all the existing environmental conventions post-Brexit, it does not follow that the legal position concerning these commitments remains unchanged. EU legislation that implements international environmental agreements has often fleshed out the broad international obligations to a considerable degree and, unless the United Kingdom decides to replicate these elaborations under national legislation, they will disappear after Brexit. More fundamentally, the position of EU law and international law within the UK national legal system is quite distinct. EU law is currently part and parcel of the UK legal system; it is applied by the national courts and overrides national law where there is conflict. Further, EU legal principles require member states to transpose obligations under EU directives into national law, giving clear national legal rights and obligations.

The position of international law in the United Kingdom is quite different. The United Kingdom operates a so-called “dualist” approach to international law, meaning that unless there is national legislation in place, one cannot invoke international legal obligations directly before the national courts. In contrast to EU legislation, there is no general legal obligation to transpose international law obligations into national law, and in the past, such obligations have often been reflected in softer instruments such as circulars or policy statements.

Increasingly, national courts refer to international law to assist in legal interpretation, but this does not change the basic position that international law itself creates no direct legal rights at a national level. It may be that post-Brexit, UK courts will be prepared to give greater weight to international legal obligations than has been the case — this development will be an important one to watch.

Post-Brexit, international environmental law will assume more significance for the United Kingdom and will represent the only supranational constraint on the freedom of the national government to act. And, until now, many such obligations have been disguised by the sharper and more immediate legal impact of the EU law implementing these agreements.

One of the unexpected implications of the Brexit process has been to reveal the importance of international environmental treaties. One hopes that post-Brexit, the United Kingdom will continue to play an active and even greater role in the development of effective international environmental law. Concurrently, it is important to consider how these commitments can be strengthened within the United Kingdom’s system of national law.

The opinions expressed in this article/multimedia are those of the author(s) and do not necessarily reflect the views of CIGI or its Board of Directors.
  • Richard Macrory is a barrister at Brick Court Chambers in London and emeritus professor of environmental law at University College London (UCL), where he set up and was the first director of the Centre for Law and the Environment.

In the Series


In Search of a Post-Brexit Trade Policy

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Brexit's Impact Will Reach Overseas

If North America and Europe don't set high standards for trade, others will set them lower

London's Financial Firms Will Suffer Post-Brexit

The European Union will keep the gate open for British financial services only as long as it needs them

How Brexit Could Undermine Human Rights

Well-established human rights standards are at risk of revision and repeal

Financial Recovery Process at Risk in a "Cliff-edge" Brexit

Defaulting to World Trade Organization rules would be a far cry from the rules of the EU single market

Brexit Could Be a Setback for Environmental Justice in the United Kingdom

According to the UN, the United Kingdom is drifting further from key environmental principles

Environmental Law Could Face Pressure Post-Brexit

Free trade deals could influence weakened environmental laws in the United Kingdom

Disentangling Intellectual Property Law Post-Brexit

Brexit will have a profound effect on trademark and design law in the United Kingdom

Where Brexit's Bold Slogans Fall Flat

The United Kingdom could "take back control" of intellectual property law — but it probably won't

Deep-rooted Environmental Law Will Burden Brexit

Transposing EU law might foster stability, but it won’t happen easily

Is No Deal the Only Deal for Brexit?

Theresa May had power to give notice of intent to withdraw from the European Union, but she needs Parliament’s authority to leave