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Limiting executive discretion after Brexit

Research by Professor Stephen Tierney enabled UK lawmakers to limit executive discretion in planning for Brexit and built vital safeguards for Parliament into the Brexit process.

EU and UK flags

Professor Stephen Tierney and Professor Mark Elliott (Cambridge) served as the two legal advisors to the House of Lords Constitution Committee, drawing from their expertise on the UK constitution and a programme of research that culminated in analysis of the European Union (Withdrawal) Act 2018 from the perspective of UK constitutional theory. Professor Tierney’s work focused primarily on the supremacy of the UK Parliament and the risks that the original European Union (Withdrawal) Bill posed to Parliament, especially to the appropriate limits of delegated powers. Stephen Tierney and Mark Elliot’s research on constitutional risks informed the Committee’s work in concrete ways and the resulting recommendations accepted by the Government had a substantial impact on the constitutional efficacy of the final Act.

Retained EU law

Professors Tierney and Elliot identified glaring inconsistencies in the status of ‘retained EU law’ and highlighted problems for legal certainty and rule of law, particularly in the Bill’s failure to make distinctions between technical matters and retained law of real substance. The Government acknowledged the importance of this issue and reshaped the status of retained EU law to delineate between ‘principal’ and ‘minor’ areas of law to which different forms of parliamentary scrutiny apply.

Court of Justice case law

Stephen Tierney and Mark Elliot also highlighted to the Constitution Committee the vague status that European Court of Justice case law would have after Brexit and emphasised how confusing this would be for Parliament’s own supremacy and for UK judges who could be drawn into political controversy. The original provision offered courts an open-ended instruction to have regard to anything decided by the European Court if considered appropriate to do so; however, Professors Tierney and Elliot recommended the provision be changed to ‘tak[e] account of matters relevant to the proper interpretation of retained EU law’. The Bill was ultimately amended, and Section 7 of the Act now adopts this relevancy test.

Delegated powers

The Bill conferred extensive delegated powers to correct ‘failures’ or ‘deficiencies’ in retained EU law, heralding a fundamental shift in power from Parliament to Government to which Professors Tierney and Elliot advanced a number of criticisms. In line with their insights with regard to breadth of power, the Government agreed to provide an ‘explanatory statement’ when making secondary law, allowing for proper Parliamentary scrutiny. They further criticised the unlimited range of discretionary powers in the Bill, signalling that these could be used in constitutionally inappropriate ways to create new public authorities or amend the devolution statutes for Scotland and Wales. The Government accepted this criticism and the Bill was amended to ensure it cannot be used for such purposes. On delegated powers, Professors Tierney and Elliot gave detailed advice to the Constitution Committee on improved scrutiny for such powers and asserted that the original provision seemed to permit very broad regulations to be made under the cover of ‘consequential’ measures. Key reforms were accepted, including stronger scrutiny for regulations that make policy changes, the creation of a ‘sifting committee’, and a 10-year sunset clause on delegated powers.