The UK Supreme Court ruled today that the UK government must hold a parliamentary vote before triggering Article 50 to leave the European Union. The ruling confirmed the November 2016 decision of the UK High Court.

The prime minister confirmed last week that the UK will leave the single market (a “hard Brexit”) and will begin the Brexit process by the end of March 2017. The immediate implication of the Supreme Court judgment is that approval from both houses of parliament (in the form of a “bill”) will be required before the process begins. There is a question whether either house of parliament will vote against the bill – given the referendum result, this is unlikely to be the case. It is also likely that the bill will be short and seek simply to approve the Article 50 notice.

However, it is likely that opposing voices in both houses of parliament will seek to delay the bill or widen the debate to encompass any of the numerous issues that arise from Brexit, including the government’s opening negotiation points. The main opposition party (Labour) has already confirmed that it will look to amend the Article 50 bill to counter any movement towards the UK withdrawing from full single market access or altering its tax regime.

Looking forward, the judgment has confirmed the limitation of the government’s powers in relation to leaving the European Union, ensuring a high level of debate in parliament at every step of the process. Further acts of parliament will be needed to enshrine the new arrangement with the EU, although their form and the likelihood of parliament devolving post-Brexit rule making powers on other UK institutions is largely unknown. It is also likely that this ruling will not be the end of Brexit legal action from interested parties.

As a win for the government, the Court did not grant any power to the national assemblies of Scotland, Wales and Northern Ireland to intervene on the decision to trigger Article 50.

The full judgment and a press summary are available here.