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The much-anticipated appeal on the Government’s right to invoke Article 50 has now been heard in the Supreme Court. In what has been widely-hailed as the most important constitutional case in recent generations, all eleven justices of the Court have heard from no less than thirteen eminent QCs, who have spoken on behalf of parties ranging from the UK Government itself to un-named children whose fundamental rights may be at stake as a result of “Brexit”.

The Court’s judgment is expected to be handed down early in the New Year. The judgment will decide once and for all whether the Government can invoke Article 50 of the Treaty of European Union simply by using the powers of the executive under the royal prerogative, or whether Parliament must first give its approval.

There now begins a period of waiting. Until January, the UK and wider world can only surmise as to how the ruling will go on this key constitutional, and politically significant, issue.

This article considers what options may be open to the Government following the Court’s judgment, whether the appeal is allowed or dismissed.

If the Government wins

In the event that the Court allows the Government’s appeal and finds that the executive has the power to invoke Article 50 by way of the royal prerogative, without any recourse to Parliament, the process should be relatively simple.

Theresa May has already made it clear that she intends to invoke Article 50 by the end of March 2017 and a Court ruling for the Government will provide her with full legal authority to do this. Parliament have this week voted to respect the Government’s timetable for triggering Article 50 and a Supreme Court judgment in support of the Government’s arguments would appear to extinguish any remaining legal barriers to the Prime Minister’s plan.

One potential headache for the Government, even if it wins the appeal, relates to the devolved powers. Counsel, acting this week on behalf of individuals from Northern Ireland, have, for example, argued that even if it is ruled that the Government can trigger Article 50 without Parliament’s input, the Northern Ireland Office must undertake an exercise under the Northern Ireland Act 1998 to enable it to advise the Government on the impact of invoking the provision on the people of Northern Ireland. If the Court were to decide that such steps are necessary, this could pose a threat to Mrs May’s timetable.

If the Government loses

The situation will be more complicated in the event that the Court dismisses the Government’s appeal and upholds the decision of the High Court, in favour of Gina Miller et al.

If the Court rules that Parliament must give its approval before Article 50 can be triggered, there are a number of ways in which the Government could seek to obtain such approval. These are summarised in the report of the House of Lords Select Committee on the Constitution– The invoking of Article 50. According to the Committee, Parliament could approve the triggering of Article 50 either by means of legislation (an Act of Parliament) or a resolution.

A resolution, either of the House of Commons or both Houses, would have the advantage that it could be agreed much more quickly than a bill. It would also bypass the potential issue of legislative consent from the devolved powers, as described below. However, according to the Committee it would not necessarily provide “water-tight” authority for invoking Article 50 against challenges in either the domestic or European courts. On the basis that it seems unlikely that the Government will want to risk being dragged through a second high-profile legal case, it seems probable that it will choose instead to draft a bill.

It has been reported that the Government was already working on a short bill in advance of the hearing and James Eadie QC, in his submissions on Day 2 of the appeal, appeared to confirm the Government’s plan:

“If the Supreme Court decides against our arguments here, the solution in legal terms is a one-line act. It may be that it would lead to all kinds of parliamentary complications and possible additions and amendments but that is the solution.”

The main advantage of an Act as opposed to a resolution is that it would provide much greater legal certainty for the triggering of Article 50, particularly when the process begun by the triggering is likely to lead to existing legislation being repealed or amended.

However, the clear disadvantage of passing an Act of Parliament is the timescale involved and the threat to the Prime Minister’s 31 March 2017 deadline. It commonly takes around a year or longer for Acts of Parliament to pass from the bill stage through both Houses and to receive royal assent before they become new law.

Built into the legislation process are numerous opportunities for the bill to be reviewed, debated and amended and, although it seems that Parliament will ultimately vote in favour of an Article 50 bill,  there will undoubtedly be attempts to make amendments.

There has already been talk of all-night debates in the Commons, with normal sitting hours suspended in an attempt to get the bill through its second reading stage. The media has reported that the Government hopes it could push the bill through the Commons in just two weeks.

Indeed, a “one-line” bill should provide much less opportunity for debate than something more substantial and this is presumably one of the reasons why the Government is contemplating so succinct a piece of legislation. In any case, there can be no doubt that the Prime Minister will seek to pull out all the Parliamentary stops to pass a bill in time for the Government to meet its March deadline.

Further delay could, however, once again come from the devolved powers. Parties from Scotland, Wales and Northern Ireland have all argued this week that the Westminster Parliament must seek approval from the governments of the devolved powers in the form of legislative consent motions.

Their argument is that the potential effects of triggering Article 50 to begin the UK’s process of leaving the EU strays into the domain of the devolved administrations and therefore a motion from each of the Scottish, Welsh and Northern Irish assemblies would be required by way of consent. Technically, these bodies could not block the legislation but the process could potentially slow down the passing of the necessary act to allow the Government to invoke Article 50.


No doubt the Justices of the Supreme Court will now spend the run up to Christmas assiduously working on what will be a momentous judgment. Until it is finalised, and handed down, there can be little certainty on how the Government will (and can) act. What does seem certain is that, for Parliament at least, 2017 is likely to begin as turbulently as 2016 has ended, especially if the judgment is not in the Government’s favour.