With the public debate on Brexit dominated by the crucial question of the form it should take, it is easy to forget how difficult Brexit is likely to be to implement through legislation. This blog post outlines some political, logistical and constitutional challenges the UK may face.

In all but the ‘softest’ scenario, the task of legislating for Brexit is going be immense. We do not yet know for sure how much primary legislation will be required, but media reports have suggested the need for upwards of seven bills, plus at least another six to cover future arrangements. The delivery of Brexit will also be unachievable without heavy reliance on statutory instruments – including some made under controversial ‘Henry VIII’ clauses (which enable primary legislation to be amended or repealed by subordinate legislation). As a result, legislating for Brexit will pose a number of potential political challenges for Theresa May’s minority government. It will also pose logistical challenges for the parliamentary timetable, and potentially raises questions about the UK’s constitutional arrangements as well.

First let us examine the political challenges. Before the recent UK general election, after scuffles in the House of Lords, the government was able to push through un-amended the Act of Parliament by which the Brexit process was officially triggered (the European Union (Notification of Withdrawal) Act 2017). It is too early to say how much less hospitable the newly constituted Parliament will be. The early indications are, however, that factions favouring ‘softer’ or more ‘open’ visions of Brexit have gained ground in the House of Commons. If the government maintains its pre-election ‘hard’ stance, the process of legislating for Brexit will present many opportunities for such factions to coalesce around particular objectives so as to interfere with the government’s proposals. An enhanced Conservative majority might have been expected to signal to the House of Lords that it should not impede the government’s Brexit business. The mixed election result may instead leave the Lords feeling emboldened to speak out. If they were to do so, it is unclear whether there would be any appetite to revisit the recommendations of the “Strathclyde Review: secondary legislation and the primacy of the House of Commons” (regarding a curtailed role for the House of Lords in scrutinising secondary legislation). There may be great reluctance to bring down the government amidst the crucial negotiations with the ‘EU27’. Even so, the new political balance seems likely to require ministers to adopt a more consensual approach to legislating for Brexit. The negotiations may, as they progress, either aggravate or alleviate the pressure to do that.

Legislating for Brexit will also test the limits of Parliament’s capacity to legislate. In their book “How to Do Things with Rules: A Primer of Interpretation” (2010 edition), William Twining and David Miers reported that the average number of government bills per year over a five year period (between 2003-4 and 2007-8) was just 35. These bills were the survivors of an intense competition for finite parliamentary time and specialist legislative drafting resources in the Office of Parliamentary Counsel (OPC). Every year for decades, in the ordinary course of advancing manifesto commitments and responding to deficiencies in the law, government departments have promoted far more legislative proposals than could be accommodated. These have had to be prioritised and winnowed. Adding a raft of Brexit legislation to the tottering pile will significantly intensify the competition in all other areas of legislative activity. Brexit legislation may, indeed, distort the parliamentary timetable rather more than the idea of having a dozen extra bills to contend with suggests. Each bill may demand greater than usual scrutiny and debate due to its complexity and potential for controversy. The likely result will be the curtailment of the government’s wider legislative programme. The forthcoming Queen’s Speech will be an interesting first indication of the potential winners and losers.

In addition to the primary legislation, hundreds of statutory instruments will need to be made in short order over the next couple of years. As Adam Chapman has recently written (see here), one hugely important feature of the forthcoming ‘Great Repeal Bill’ will be the framing of powers for making secondary legislation. This will affect the extent to which that legislation is subject to parliamentary and judicial control. Regarding parliamentary control, Richard Kelly’s Briefing Paper number 06509 “Statutory Instruments” (2012 and 2016 editions) explains that, leaving aside Brexit, there are already “about 3,500 SIs each year, varying in size from a single sheet to several hundreds of pages”. The vast majority of these are not subject to material parliamentary scrutiny. The most common form of scrutiny is the ‘negative resolution procedure’ where the secondary legislation is laid before Parliament and may be negated if a motion to annul is passed within 40 days. One potential consequence of there now being a minority government may be that legislators push for affirmative or super-affirmative procedures to be introduced into delegated powers to facilitate heightened parliamentary scrutiny of, and amendments to, secondary legislation. This might offer an alternative to Parliament negating statutory instruments. Where such procedures exist today, however, the burden of oversight often falls on already stretched parliamentary Committees and the time for debate over statutory instruments is generally very short. Quite apart from the demands of drafting many more statutory instruments, therefore, Brexit will strain democratic legislative oversight to its limit.

Secondary legislation is, of course, principally produced by the executive, not the legislature. A substantial increase in legislation by that route, especially under ‘Henry VIII’ clauses, therefore also raises constitutional questions. What will it mean for the balance between executive and legislature, and indeed for devolution? Where parliamentary scrutiny is ineffective, judicial oversight may come to the fore through judicial review. New legal ground is likely to be broken in circumstances where statutory instruments may play a role traditionally reserved for primary legislation. That is particularly so if the secondary legislation prescribes results to be achieved rather than simply setting out rules to be used to achieve those results – since this will effectively delegate the important detail of Brexit to be worked out, without the slightest parliamentary scrutiny, by the executive arm of the state. If Brexit legislation were very often to be tempered in the fire of the courts, this too might unsettle our separation of powers. How well would our pragmatic, flexible constitution withstand the judges frequenting (more than they do now) the places where law and politics intersect?

In the immediate aftermath of the 2017 general election, the debate over whether the UK should pursue a ‘softer’ Brexit has been reinvigorated. That question is of course fundamental. It should not, however, prevent the forthcoming political, logistical and constitutional challenges of legislating for Brexit from being identified and addressed. With the Article 50 clock already ticking, the critical path to delivering the legal framework for Brexit threatens to be almost as testing for the new minority government as the forthcoming negotiations.