Opinion: Parliament needs to load the Article 50 gun before Prime Minister triggers Brexit

In a landmark constitutional judgment handed down today, the Supreme Court has ruled by 8-3 that Prime Minister Theresa May has no legal power to trigger Article 50 of the Lisbon Treaty, and must seek statutory authorisation from Parliament.

For the Prime Minister to meet her own self-imposed deadline of triggering Article 50 before the end of March, Parliament will need to adopt legislation quickly to put the Brexit bullet in the Article 50 barrel.

Nothing in today’s Supreme Court ruling can ultimately prevent the UK Government from triggering Article 50. Once Parliament has legislated, Brexit will begin.

But the decision of the majority of the Supreme Court judges is controversial. Voters will be astonished that they voted in a referendum without the Government having the legal power to implement their wishes if the country voted to leave the EU.

The case was brought by Gina Miller, an investment manager (the ‘lead claimant’), together with Mr Deir Dos Santos, a hairdresser, both UK citizens resident in the UK. Their claim was supported by a crowd-funded claim – the so-called ‘People’s Challenge’ – in the name of Graeme Pigney and other UK citizens resident in different parts of the UK and in other EU states.

The Scottish Government will be disappointed with the ruling because, unanimously, the Supreme Court did not accept that the Scottish Parliament must give its consent before Westminster legislates on Brexit.

SNP MPs may seek to add amendments to the Brexit Bill to be passed by Parliament. These amendments may include a requirement that Holyrood gives its consent to the triggering of Article 50, or may even go so far as to provide a legal basis for a second independence referendum. Although any such amendment would have no hope of being passed, their rejection by Westminster might be used as evidence by the SNP that Scotland’s future lies inside the EU, but outside the UK.

In her Lancaster House speech last week, the Prime Minister accepted that both Houses of Parliament will be given a vote on the withdrawal agreement once the Brexit negotiations have ended.

Any risk of Parliament derailing Brexit will come at the end of the Article 50 process, rather than the beginning. And that could lead the UK into an early General Election, throwing the whole withdrawal from the EU into chaos.

Kenneth Armstrong is Professor of European Law at the University of Cambridge. His new book, Brexit Time, will be published by Cambridge University Press in the Spring.