The UK prime minister, Theresa May, has given the most detailed speech on the future EU-UK security relationship delivered since the Brexit referendum in June 2016. The speech included a major concession at a crucial moment for relations between the pro and anti-EU wings of her party. Addressing an audience of international security ministers and wonks, May accepted that “when participating in EU agencies the UK will respect the remit of the European Court of Justice”.

May used the speech to flesh out an idea originally floated in her Florence speech of September 2017, when she proposed a “security treaty”. This would involve post-Brexit EU-UK foreign, security and defence collaboration highly integrated as one part of a “deep and special” partnership between the EU and the UK.

The message was that the UK is seeking a significant degree of post-Brexit security integration. In fact, this is one area of Brexit policy in which the goal is to retain a relationship as close as possible to being a member state. This is in significant contrast to the current thinking on trade, given that the government’s current position is to leave both the single market and customs union.

Deep collaboration

Security is complex in the EU – there are different degrees of integration between different countries and various different EU treaty articles. Even the EU-level policy is pursued across different institutions. The European Commission, other EU agencies and member states all play different roles. This throws up considerable legal and practical difficulties for a non-member state. The prime minister partly wished this away in her speech with a statement about not allowing “rigid institutional restrictions or deep-seated ideology to inhibit our co-operation”.

But reading the text closely, May also appeared to cross one of the government’s red lines by accepting that the UK must adhere to the rulings of the ECJ. This is essential if the UK wishes to preserve the closest possible relationship with the EU and its member states, collaborating on crime and terrorism through agencies such as law enforcement agency Europol and judicial agency Eurojust.

Sharing information with EU member states in these areas means access to data systems such as Schengen Information System and Prüm treaty on terrorism and cross-border crime. All are subject to judicial oversight by the ECJ. Continuing to use the European Arrest Warrant will also mean conforming with the EU’s legal order.

Opposition to this detail in the speech from hard Brexit-supporting members of the Conservative Party has so far been muted – but it is a major concession. Leaving the ECJ after Brexit has become a central argument for those who think that leaving the EU means “taking back control” of lawmaking. Any continuing influence for the court is a difficult sell for May. The lack of backlash may suggest the Brexit wing of her party hasn’t fully digested the news.

EPA

There is strong advocacy for preserving existing policing and intelligence links via European agencies. This was signalled with a joint statement issued by French, German and UK intelligence chiefs meeting in the margins of the Munich conference that stressed the need to avoid any dislocation in their current relationships.

But May offered less detail on what happens during the transition period that begins in March 2019. Unless alternative arrangements are made, as a non-member state the UK will depart the EU decision-making structures but will still have to comply with EU decisions on major foreign policy issues.

The prime minister has provided important details on how the UK envisages a high degree of cooperation with the EU after Brexit. Munich is the largest annual gathering of security officials. Choosing to deliver such a strident message on the UK government’s aspirations was a serious declaration of political intent.

Nevertheless, a non-member state cannot expect to be as integrated into EU decision making on foreign, security and defence policy as a full member state. The UK government’s new enthusiasm for cooperation in this area sits at odds with its history of low-level participation and its resistance to deepening integration in these areas – and at a time when it is talking about severing ties in all kinds of other areas.