Mark Elliott and Stephen Tierney: Sovereignty or Supremacy? Lords Constitution Committee Reports on EU (Withdrawal) Bill

The House of Lords Constitution Committee today issues its main report on the European Union (Withdrawal) Bill. This follows the preliminary and interim reports on the Bill that the Committee published last year. The new report is wide-ranging and hard-hitting, the Committee’s view being that the Bill ‘risks fundamentally undermining legal certainty’. In this post, we make no attempt to summarise the report. Rather, we focus on two key and interlocking chapters that address the legal nature and constitutional status of the new body of domestic law — ‘retained EU law’ — that the Bill will create. In doing so, we highlight the Committee’s view that central parts of the Bill are ‘conceptually flawed’ and that relevant retained EU law should be reconceived by treating it as if it were contained in an Act of Parliament enacted on ‘exit day’.

Legal nature of retained EU law

The Committee distinguishes between two categories of retained EU law: ‘EU-derived domestic legislation’ as defined by clause 2, and directly effective EU law that will be made part of domestic law on exit day by clauses 3 and 4. For convenience, the Committee uses the term ‘retained direct EU law’ to refer to the latter, albeit that that is not a term used by the Bill; we adopt that term for the purpose of this post. As far as its legal nature is concerned, EU-derived domestic legislation is straightforward: it is ‘already either domestic primary legislation or domestic secondary legislation; and under the Bill, it will have the same status post-exit as it had pre-exit’. Retained direct EU law, however, is a different kettle of fish: it does not correspond to any pre-exit law that currently has an established domestic status, and yet ‘[t]he Bill is silent’ as to the post-exit position as regards such law.

In evidence to the Committee, the Government argued that because retained direct EU legislation under clause 3 (and presumably, by extension, all retained direct EU law) ‘was not made by UK legislators’, it will ‘have a unique status within the domestic hierarchy’ such that it should be treated as neither domestic primary nor secondary legislation. The Committee, however, rejects this analysis. ‘Retained direct EU law,’ it points out, ‘will be domestic law’, and there is ‘no reason why Parliament cannot or should not assign to retained direct EU law a recognisable domestic legal status’. The Committee goes on to observe that ‘[t]he fact that retained direct EU law originated outside the domestic legal system’ does not constitute a ‘good reason for neglecting to assign it a domestic legal status once it is recognised as domestic law’.

The Committee is particularly critical of the Government’s intention that powers under clause 17 should be used, at the discretion of ministers, to determine the legal status of individual pieces of retained direct EU law. ‘It is constitutionally unacceptable,’ says the Committee, ‘for ministers to have the power to determine something as fundamental as whether a part of our law should be treated as primary or secondary legislation.’ The Committee also finds concerning the fact that the Bill does assign (either directly or obliquely) domestic statuses to retained direct EU law for limited purposes. Thus, for instance, it is primary legislation for Human Rights Act-related purposes, but (in effect) secondary legislation so far as its vulnerability to the use of delegated powers outwith the Bill is concerned. The upshot, says the Committee, is that retained direct EU law will have a given status for some purposes, a different status for other purposes, and no status at all for yet further purposes. This, it concludes, is ‘a recipe for confusion and legal uncertainty’.

What, then, is to be done? The Committee’s central recommendations in this regard represent a radical break with the Bill as presently drafted: all retained direct EU law should have the same legal status: namely, that of domestic primary legislation. The Committee acknowledges that this approach ‘is not without constitutional costs’, noting, for instance, that it would shield retained direct EU law from strike-down on HRA grounds (something that is already anticipated by the Bill) and from judicial review on common law grounds. However, the Committee observes that retained direct EU law with the status of primary legislation would remain subject to judicial interpretative and declaratory powers under the HRA, and to the courts’ inherent powers of construction whereby legislation is, wherever possible, read in line with common law constitutional norms.

Ultimately, the Committee concludes that any constitutional costs of treating all retained direct EU law as primary legislation are far outweighed by the gains. Those gains most obviously include clarity, simplicity and legal certainty. But they also extend to the protection of retained direct EU law against the use of many delegated powers conferred by legislation other than this Bill. Indeed, treating retained direct EU law as primary legislation would make it invulnerable to all delegated powers other than Henry VIII powers. The Committee recognises that this would make ‘even technical and mundane elements of retained direct EU law immune from the use of non-Henry VIII delegated powers’, but concludes that it is infeasible to ‘lay down in the Bill any formula capable of satisfactorily distinguishing between retained direct EU law that should be treated for this purpose as primary legislation and that which should be treated as secondary legislation’. It therefore applies a ‘constitutional precautionary principle’ that leads it to the conclusion that all retained direct EU law should be regarded as primary legislation. This, it says, will ‘protect important legal norms and rights from revocation by the use of delegated powers which are not Henry VIII powers and which, as such, are often subject to lesser forms of parliamentary control and scrutiny than are Henry VIII powers (which are usually subject to the affirmative procedure)’.

Constitutional status of retained EU law

The recommendation that retained EU law be treated as primary legislation is also central to the Committee’s assessment of clause 5, which seeks to ascribe a ‘supremacy principle’ to retained EU law. The combined effect of clause 5(1) and (2), at least as intended by the Government, is that the ‘supremacy principle’ will not operate in relation to legislation that is enacted on or after exit day but will operate in relation to legislation that is enacted prior to exit day. The Committee supports the policy aim that underpins clause 5, namely the attempt to avoid the destabilisation that would result if, upon exit, pre-exit domestic law suddenly prevailed for the first time over retained EU law. However, it is highly critical of the approach taken by the Bill to secure this goal. In the Committee’s view, the very notion of the supremacy of retained EU law is ‘conceptually flawed, sits uncomfortably with the doctrine of parliamentary sovereignty and is a potential source of legal confusion’. Therefore, it recommends removal of the supremacy principle from the Bill, arguing that retained EU law can be given precedence over pre-exit domestic law more effectively and more logically through the use of principles of domestic law.

The Committee identifies three major problems with clause 5. The first lies in attempting to define the scope of the ‘supremacy principle’. In evidence to the Committee, the Solicitor General appeared to take the view that retained EU law would benefit from the ‘supremacy principle’ (in respect of pre-exit domestic law) only if it corresponds to pre-exit EU law that itself benefitted from this principle. This would mean in effect that retained direct EU law under clauses 3 and 4 would enjoy the post-exit ‘supremacy principle’ but not EU-derived domestic legislation under clause 2. The Committee considers this a sensible approach, corresponding as it does to the current position as regards EU law. However, the Bill is not explicit on this point and therefore the Committee recommends that if references to the ‘supremacy principle’ are to be preserved in the Bill, then clause 5 should be amended ‘to set out clearly the intended scope of the principle.’

A second concern is that it is not clear when the ‘supremacy principle’ is intended to bite upon other forms of domestic law. Clause 5(2) is broadly worded, and it was suggested to the Committee by the Solicitor General that the ‘supremacy principle’ applies not only to legislation but also to the common law. The Committee however draws attention to the difficulties with such a construction, not least due to the evolving nature of the common law. What is meant by common law ‘made before exit day’ (per clause 5(2))? When judges articulate ‘new’ common law rules or principles are they in fact making new law or merely declaring the common law as it has always been? Again the Committee concludes that, if references to the ‘supremacy principle’ are to be preserved in the Bill, an amendment on this point would be needed in the interests of legal certainty.

Despite suggesting these amendments, the Committee’s preferred solution is the removal of the ‘supremacy principle’ altogether. The Committee notes that what the Bill calls ‘the principle of the supremacy of EU law’ only applies in the UK ‘because, and to the extent that, Parliament has so provided’ in the European Communities Act 1972: a fact recognised in domestic jurisprudence and in the European Union Act 2011, s 18. The ‘supremacy principle’ is a principle of EU law and only has meaning and application in relation to EU law. Since retained EU law is domestic law, it makes no sense to think that the principle of the supremacy of EU law can attach to it.

The Committee proceeds to formulate a means by which retained EU law can be given priority over pre-exit domestic legislation in a way consistent with UK constitutional principle. The Committee reiterates its recommendation that retained direct EU law should be given the status of an Act of the UK Parliament. However, it now supplements this proposal with a crucial temporal element: retained direct EU law should be treated as having the status of an Act of the UK Parliament enacted on exit day. In this way retained direct EU law would prevail over earlier inconsistent legislation, while subsequent inconsistent legislation would prevail over it. In other words, the aims of clause 5 would be met in a way that is entirely consistent with parliamentary sovereignty. In this way the uncertainty concerning the operation of the ‘supremacy principle’ upon common law ‘made before exit day’ would also be removed. The relationship between retained direct EU law and the common law would operate according to the well-established constitutional principles that already govern the relationship between Acts of Parliament and the common law.


Despite its critique of clauses 2-5, the Committee’s recommended amendments are framed constructively. The Committee recognises the Government’s key aims and seeks to propose ways in which these might be pursued in a clearer way, reducing the risk of legal confusion in the definition, effects and constitutional status of retained EU law.

The key recommendation that retained direct EU law be treated as having the status of an Act of Parliament enacted on exit day would, in the words of the Committee, ‘greatly simplify’ retained EU law’s constitutional position ‘by ascribing to it a status consistent with the doctrine of parliamentary sovereignty. It would also complete the task of excising EU law from domestic law by making clear that retained direct EU law is, after exit day, domestic rather than EU law, subject only to the doctrines and principles of the UK constitution and not in any way contingent for its status upon the externally-derived constitutional doctrines of the EU.’ Since one of the Government’s goals is to reassert Parliament’s supremacy in the wake of the UK’s exit from the EU, it would appear that the recommendations set out in the report offer a means of doing so in a way that is more coherent in both conceptual and practical terms than the current provisions of the Bill. None of this is about ‘blocking Brexit’. Rather, it is about enabling the UK’s departure from the European Union to take place in a legally coherent way that will maximise legal certainty, secure (where appropriate) legal continuity, and ensure that the Bill operates in a way that is consistent with well-established domestic constitutional principles.

Mark Elliott is Professor of Public Law at the University of Cambridge. Stephen Tierney is Professor of Constitutional Theory at the University of Edinburgh. They both serve as Legal Advisers to the House of Lords Constitution Committee. This post, however, is written purely in their personal capacities.

(Suggested citation: M. Elliott and S. Tierney, ‘Sovereignty or Supremacy? Lords Constitution Committee Reports on EU (Withdrawal) Bill’, U.K. Const. L. Blog (29th Jan. 2018) (available at