As outlined in our summary of the High Court case, the majority of the Supreme Court ruled that an Act of Parliament was required by the Government to serve the Article 50 notification to withdraw from the European Union. The Supreme Court also unanimously decided that the devolved administrations (Wales, Scotland and Northern Ireland) were not required to provide consent to the withdrawal from the European Union.
Thus it seems clear now that the Government will need to go through Parliament before serving Article 50 (EU Treaty) notice to leave the EU. This need not change the final outcome, and most commentators agree that any effective block on a motion to serve Article 50 notice quickly from this point would not be likely. However this verdict does underline the need for the Government to consult Parliament, and it is to be hoped that improved levels of informed and transparent analysis through Parliament of the thoroughly complex issues involved will lead to better resolution of those issues in the long term.
We now consider the most commonly asked questions following this verdict:
Can the Government serve the Article 50 notification without an Act of Parliament?
No. The Government relied upon the argument that the royal prerogative power to enter into international treaties (such as the EU Treaties) meant that it also had the power to withdraw from the same. However, the claimants relied upon the argument that this power did not apply in this instance, as one of the key restrictions placed upon the royal prerogative power is that it cannot affect domestic law and remedies. The majority of the Supreme Court agreed with the claimants and stated that an Act of Parliament would be required.
Lord Neuberger, delivering the judgment, agreed with the initial High Court ruling, stating that UK citizens enjoy a variety of rights and remedies via sections 2(1) and 2(2) of the European Communities Act 1972, and that serving the Article 50 notification would "pull…the trigger which causes the bullet to be fired, with the consequence that the bullet will hit the target and the (EU) Treaties will cease to apply". Even if the proposed Great Repeal Bill were to seek to immediately replicate the primary rights and remedies currently available to UK citizens via the EU treaties, this could not be taken into account by the Supreme Court in its decision and in fact strengthened the argument that UK citizens received rights in domestic law as a result of the EU Treaties.
It is important to note that the majority of the Supreme Court also agreed that an Act of Parliament (approved by both the House of Commons and the House of Lords) would be required – not a simple motion, similar to that passed by the House of Commons in December – to provide the Secretary of State with the ability to issue the Article 50 notification on behalf of the UK.
Does this mean that the referendum result is overturned?
No. The Supreme Court repeated on multiple occasions that this was a (UK) constitutional law matter. A referendum does not by itself bind the UK into taking one form of action or another – by default it is simply advisory, unless the Act of Parliament governing the referendum requires the government to take certain actions. The European Union Referendum Act 2015 in this instance did not require the government to take any action, but previous referendum acts (concerning Scotland and Northern Ireland, for example) have stated what must happen in the event of a certain vote.
Does Westminster have to obtain the consent of the UK's devolved administrations?
No. The United Kingdom's withdrawal from the EU will affect the arrangements that Westminster has with the Scottish Government, Welsh Assembly and the Northern Irish Assembly as EU legislation affects a number of key areas delegated to the regions. There is an expectation (known as the Sewel Convention) that if Westminster passes legislation that affects something explicitly affecting matters devolved to Northern Ireland or Scotland, a consultation process will usually be required. However, the Supreme Court stated that the Sewel Convention could not be enforced in court as it was a political expectation rather than a law – even if that convention was referred to within the Scotland Act.
The next steps
In order to serve the Article 50 notification, an Act of Parliament will need to be passed by the House of Commons and the House of Lords. Whilst the Government has suggested it will submit a short and simple bill in the hope that that its ambition of serving Article 50 notice by the end of March 2017 can be preserved, this may be affected by the all party Brexit committee report which suggested that the Government should publish a White Paper that reflects the Government's position (similar to Theresa May's recent speech on her initial negotiation position) followed by a series of debates prior to the serving of the Article 50 notification. In the meantime, the preparation work for the Great Repeal Bill will take greater significance as civil servants are faced with the unenviable task of collating all European legislation to ensure that it still applies to the UK immediately post Brexit. Finally, observers should keep a keen eye on the legal challenge brought in the Republic of Ireland which if successful could force the European Court of Justice to declare whether an Article 50 notification can be unilaterally reversed at a later stage.