Faculty of law blogs / UNIVERSITY OF OXFORD

Eleven Types of post-Brexit EU Law


Time to read

10 Minutes

The United Kingdom and the European Union agreed on Christmas Eve a new Trade and Cooperation Agreement. This treaty has replaced the rules of the single market in the UK (with the exception of Northern Ireland and Gibraltar). It is, however, only one part of EU law in the United Kingdom. EU law in the UK is now a matter of a multiple and overlapping legal instruments. Post-Brexit legal arrangements are very complex, perhaps surprisingly so. Although it is not possible to set out these matters here in detail, it would perhaps be worth listing the eleven types of EU law operating in the United Kingdom after Brexit.  

The EU-UK Trade and Cooperation Agreement (2020)

The first such type of law and the broadest is the Trade and Cooperation Agreement between the EU and the UK (OJ L 444/14, 31.12.2020)  (TCA). It is accompanied by a Nuclear Cooperation Agreement (NCA) and a Security of Classified Information Agreement (SCIA), which were agreed at the same time, but I leave these to one side. The TCA’s ratification by the EU will be completed in February or March by the European Parliament. Until then it is applied only provisionally. It is not intended to be ratified by the member states, since it is not taken to be a mixed agreement. 

In terms of its substance, the TCA covers institutional provisions (setting up a partnership council and various committees of negotiation),  trade and other economic aspects of the relationship (such as aviation, energy, environment, road transport, and social security),  cooperation on law enforcement and criminal justice, health collaboration, participation in EU Programmes, dispute settlement and final provisions (for an introduction, see Steve Peers’ illuminating presentation). It is envisaged that the TCA will be supplemented in due course by way of future bilateral agreements on other areas. 

In general, the legal features of the TCA are as follows: 

  • The TCA is not enacted under the Article 50 process of withdrawal. 
  • It is a new international treaty between the EU and the UK, hence an ‘external EU treaty’ under Articles 216 and 217 TFEU (it appears that the EU is considering this an ‘Association Agreement’ under Article 217 TFEU).
  • The TCA does not intend to create directly effective rights to individuals. So whatever obligations the EU now has not to impose tariffs and quotas, these are owed to the UK government, not to individuals engaged in trading (see Article COMPROV.16: Private rights).
  • The TCA is an international agreement to create a Free Trade Zone, and is therefore subject to the general conditions of the World Trade Organization, of which both parties are members. 
  • There is no role for the CJEU.
  • Either the UK or EU may decide to terminate the Agreement with 12 months’ notice.

In the United Kingdom’s summary of the TCA it is stated (at par. 13, at par. 171)  that the institutional provisions ‘remove any ambiguity about the UK’s status as a sovereign nation’. This is a misleading statement. There was never any such ambiguity. There is no legal doubt of the sovereignty of any member state of the European Union under the Treaties, as confirmed most recently in the Wightman judgment of the CJEU.

The TCA was incorporated into UK law by the European Union (Future Relationship) Act 2020, which in s. 29 provides that the agreements have immediate domestic effect, even if they are not otherwise implemented: 

(1) Existing domestic law has effect on and after the relevant day with such modifications as are required for the purposes of implementing in that law the Trade and Cooperation Agreement or the Security of Classified Information Agreement so far as the agreement concerned is not otherwise so implemented and so far as such implementation is necessary for the purposes of complying with the international obligations of the United Kingdom under the agreement.

This is an unusually open-ended provision, which establishes not only some kind of direct effect for the TCA, but also some primacy towards all domestic law. This follows from the use of the term ‘modifications’. It is unclear how far this broad and unusual provision will have an impact on the law of the UK, given that the TCA does not create directly effective rights. 

The EU-UK Withdrawal Agreement (2019)

The second type of EU law with continuing effect in the UK is that created by the EU-UK Withdrawal Agreement (WA), signed on 12 November 2019. The subject matter of the EU -UK Withdrawal Agreement is limited. It concerns citizens’ rights, the financial arrangement, various transitional arrangements, separation issues and the status of Northern Ireland. What is unique about this instrument is that, unlike the TCA, it is not strictly a treaty between the two parties. Since it was concluded by the EU and the UK while the UK was still a member, it was made through EU law under the sui generis process of Article 50 TEU. It therefore needed no ratification by the EU or its members (which a treaty would have required). It is, it seems to me, just part of EU law as a sui generis modification of the EU treaties. 

In general, the legal features of the WA are as follows: 

  • The WA is part of the Article 50 process of withdrawal and part of EU law. 
  • It is not, therefore, a standard treaty of public international law international treaty between the EU and the UK  (although it could also be seen as one).
  • The WA is meant to create directly effective rights to individuals and especially EU citizens in the UK and UK Citizens in the EU.
  • The WA is meant to enjoy primacy over UK law.
  • The WA created a transitional period within which EU law applied directly in the UK.
  • The WA creates a distinct governance structure regarding withdrawal matters including a ‘Joint Committee’.
  • For eight years from the end of the transition UK courts may send preliminary references to the CJEU on matters relating to EU Citizens’ rights.

It is important to stress that the WA is supposed to have direct effect and primacy in the UK. Article 4 of the WA provides that: 

‘The provisions of this Agreement and the provisions of Union law made applicable by this Agreement shall produce in respect of and in the United Kingdom the same legal effects as those which they produce within the Union and its Member States. Accordingly, legal or natural persons shall in particular be able to rely directly on the provisions contained or referred to in this Agreement which meet the conditions for direct effect under Union law’. 

The WA was given effect in the UK by virtue of sections 5 and 6 of the European Union (Withdrawal Agreement) Act 2020 (‘the 2020 Act’), which amended in various ways and inserted new sections 7A and 7B to the European Union (Withdrawal) Act 2018 (‘the 2018 Act’), which remains the main act on the status of EU law after exit day. 

The most important provisions of these Acts were commenced on ‘implementation period completion day’ (ie 11 pm on 31 December 2020) under The European Union (Withdrawal) Act 2018 and European Union (Withdrawal Agreement) Act 2020 (Commencement, Transitional and Savings Provisions) Regulations 2020, enacted on 21 December 2020). 

Five Categories of ‘EU Retained Law’ (as of 31 December 2020)

The third major category of EU law may be the most extensive and can be subdivided into five different sub-categories, each with a distinct legal basis (for which see Jack Williams’ enlightening blog post). The European Union (Withdrawal) Act 2018 Act (‘the 2018 Act’) created the broad category of ‘EU retained law’. This is the law that applied to the UK at the time of its full departure from the EU (with the exception of the EU Charter of Fundamental Rights). All such law the 2018 Act protects from immediate demise on departure. This covers primary and secondary law. Any later amendments to EU retained law by the EU will not, naturally, be applicable to the UK. 

Section 5(2) of the 2018 Act provides that the supremacy of EU law applies to any enactment or rule of EU law ‘so far as relevant to the interpretation, disapplication or quashing of any enactment or rule of law passed or made before exit day’. In other words, supremacy is still a relevant principle for all EU retained law. 

According to s.6(7) of the 2018 Act retained EU law means: 

‘anything which, on or after exit day, continues to be, or forms part of, domestic law by virtue of section 2, 3 or 4 or subsection (3) or (6) above (as that body of law is added to or otherwise modified by or under this Act or by other domestic law from time to time);’

This creates the following five sub-categories of ‘EU retained law’. 

  1. ‘EU-derived domestic legislation’ 
    Under s. 2 of the 2018 Act EU-derived domestic legislation is any primary legislation created in order to give effect to EU law obligations or secondary legislation made under the enabling provisions of the European Communities Act 1972, or ‘relating otherwise to the EU or the EEA’. Strictly speaking, of course, there was no need to ‘save’ primary law, but the Act is doing so anyway.
  2. ‘direct EU legislation’ 
    Under s. 3 of the 2018 Act, ‘direct EU legislation, so far as operative immediately before exit day, forms part of domestic law on and after exit day’. Section 3(2)(a) specifies that direct EU legislation includes regulations and decisions, but not directives. Section 5(4) explicitly excludes the Charter of Fundamental Rights from EU retained law.
  3. ‘rights etc. under section 2(1) of the ECA’
    Under s.4 of the 2018 Act, ‘any rights, powers, liabilities, obligations, restrictions, remedies and procedures which, immediately before exit day (a) are recognised and available in domestic law by virtue of section 2(1) of the European Communities Act 1972, and (b) are enforced, allowed and followed accordingly, continue on and after exit day to be recognised and available in domestic law (and to be enforced, allowed and followed accordingly)’. This is a provision, effectively incorporates the whole of EU law into UK law. It has made it necessary for UK ministers to legislate to exclude various aspects of the Treaties from the status of ‘EU retained law’. For example, The Freedom of Establishment and Free Movement of Services (EU Exit) Regulations 2019 removed Articles 49,  56 and 57 TFEU and Articles 36 and 37 of the EEA Agreement from retained EU Law.  Section 4(2) of the 2019 Act creates an exception, however, for rights that arise under an EU Directive ‘and are not of a kind recognised by the European Court or any court or tribunal in the United Kingdom in a case before exit day (whether or not as an essential part of the decision of the case)’. It follows, I suppose, that directly effective directives continue to have direct effect under s. 4 of the 2018 Act.
  4. ‘Retained case law’ 
    Section 6 of the 2018 Act provides that although the Supreme Court of the UK is not ‘bound’ by any retained EU case law (s. 6(4)), any question as to the validity, meaning or effect of any retained EU law is to be decided so far as this law is unmodified on or after the ‘implementation period completion day’, ie 31 December 2020, and so far as it is relevant to it (a) in accordance with any retained EU case law, and any general principles of EU law and (b) having regard (among other things) to the limits, immediately before IP completion day, or EU competences. At 6(7) the term ‘retained case law’ is defined as (a) retained domestic case law and (b) retained EU case law.
  5. ‘Retained general principles of law’ 
    As we saw above, s. 6 of the 2018 Act provides that ‘retained general principles of law’ are relevant in the interpretation and application of EU retained law. These principles are defined in s 6(7) as: the general principles of EU law, as they have effect in EU law immediately before IP completion day and so far as they—(a) relate to anything to which section 2, 3 or 4 applies, and (b) are not excluded by section 5 or Schedule 1, (as those principles are modified by or under this Act or by other domestic law from time to time).

EU Law in Northern Ireland 

The eighth category of EU law is the single market that will continue to apply to the UK on the basis of the Protocol on Ireland/Northern Ireland. Under the Northern Ireland Protocol the following domains of EU law still have effect in Northern Ireland and remain under the jurisdiction of the CJEU: customs and movement of goods (Article 5 of the Protocol); technical regulations, assessments, registrations, certificates, approvals and authorisations (Article 7 of the Protocol); VAT and excise (Article 8 and Annex 3 of the Protocol); single electricity market (Article 9 and Annex 4 of the Protocol); state aid (Article 10 and Annex 5 of the Protocol). Article 12(4) of the Protocol states that, in relation to these provisions ‘the institutions, bodies, offices, and agencies of the Union shall in relation to the United Kingdom and natural and legal persons residing or established in the territory of the United Kingdom have the powers conferred upon them by Union law’. 

‘Relevant Separation Agreement Law’

The ninth category is not strictly speaking a distinct legal category, since it consists of domestic secondary law. Nevertheless, its interpretation must follow the Withdrawal Agreement in a special way, subject to EU law (under the general terms of the WA). Section 26(2) of the European Union (Withdrawal Agreement) Act 2020  creates the category of ‘relevant separation law’ by inserting a new s.7C to the 2018 Act. According to s.7C “relevant separation agreement law” means either some general parts of the 2018 Act itself or Part 3, or section 20, of the European Union (Withdrawal Agreement) Act 2020 (citizens' rights and financial provision), or any domestic law that relates to the withdrawal agreement. It covers therefore any secondary legislation made in order to give effect to the WA. The significance of the designation ‘relevant separation agreement law’ is that its application must be in line with the underlying Withdrawal Agreement. Any question as to the validity, meaning or effect of any relevant separation agreement law is to be decided, ‘in accordance with the withdrawal agreement, the EEA EFTA separation agreement and the Swiss citizens' rights agreement’.  

Secondary EU ‘Exit Law’ 

The tenth category is also a branch of domestic secondary law. It consists of the voluminous items of delegated legislation that deal with the practicalities of Brexit and are created under the 2018 Act. A quick search in January 2021 showed that as of early January 2021, there were 826 UK Statutory Instrument with the terms ‘EU Exit’ in their titles (from ‘The Machine Games Duty (Amendment) (EU Exit) Regulations 2018 of 18 July 2018, to ‘The Organic Production (Organic Indications) (Amendment) (EU Exit) Regulations 2020, dated ‘at 11.07 p.m. on 31st December 2020’). This category is highly relevant to EU law, because it sets out which parts of EU ‘retained’ law is not effective in the United Kingdom. 

Secondary ‘Trade and Cooperation Law’ 

Finally, sections 31 to 33 of the European Union (Future Relationship) Act 2020 create broad powers for ministers of the Crown to create further secondary legislation in order to give effect to the TCA. The precise content of these statutory instruments will be interpreted in light of the TCA.


While the UK was a member of the EU, European law applied in a streamlined fashion, under the terms of the European Communities Act 1972. The withdrawal of the UK from the EU has resulted in a very complex legal framework. EU law will continue to apply to the UK, most visibly in Northern Ireland, but also in the other parts of the UK in eleven different ways, as outlined above. The relevant legal instruments include one EU Treaty, one international treaty, at least three major Acts of Parliament of wide scope and hundreds, if not thousands, of items of secondary law.


Pavlos Eleftheriadis is a barrister at Francis Taylor Building and a professor of public law at the University of Oxford


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