Supreme court inflicts Brexit blow to Theresa May

Her determination to fight issue of parliamentary approval way has betrayed lack of judgment

The supreme court has ruled that the British government must enact a Bill in parliament before it can trigger Article 50, the legal pathway to Brexit. The court's decision is a blow to Theresa May but it is unlikely to derail her plan to invoke article 50 before the end of March.

If anything, the supreme court's decision will be greeted with relief by ministers. The court could have ruled that the devolved administrations – Scotland, Wales and Northern Ireland – should give their assent to article 50 invocation before Ms May pressed ahead. Had such a judgment been delivered, it would certainly have fouled up the prime minister's timetable, given the strong opposition to Brexit in Scotland. That course has been rejected.

David Davis, the Brexit minister, must now bring a Bill before parliament for rapid assent. It is inconceivable that MPs and peers will vote it down. To do so would defy the will of the majority of British people at the referendum. Opinion polls show no sign that the majority for Leave has diminished.

Even so, there are two issues that now have to be watched closely in parliament.

The first question is whether MPs end up amending the Bill to tie Ms May's hands in the forthcoming negotiation. Labour is pondering such a move and the Scottish National Party has already said it will table 50 "serious and substantive" amendments.

Some MPs want the Bill to guarantee that access to the European single market is prioritised over controls on immigration. This runs against the thrust of Ms May’s position and they are unlikely to succeed. A more interesting issue is whether Labour can force an amendment that clarifies what would happen if MPs reject Ms May’s final deal with the EU in 2018. Would Britain automatically fall out of the EU? Or can Brexit somehow be reversed?

Secondly, how united will Labour be in the final vote? Party leader Jeremy Corbyn has insisted that his MPs back the Bill invoking article 50. But many Labour MPs want to vote against article 50 outright. A substantial revolt by Labour MPs could be another blow to his leadership.

Article 50's journey through the UK courts has been a sorry story for the government. With hindsight, the prime minister would have been wiser to state last July that parliament should have a vote, daring MPs to defy her. Once the High Court had ruled against her last year, she should have accepted its judgment instead of prolonging matters at a cost to the taxpayer. Her determination to fight the matter all the way has betrayed a lack of judgment.

However, Ms May’s recent speech setting out her negotiating principles has restored momentum to the prime minister. The big question – going much wider than matters of parliamentary procedure – is whether she is pushing the negotiation timetable with the EU too fast. Many fear she is plunging into talks that cannot produce the ambitious new trade treaty she seeks against the deadline she must meet. If her negotiation fails, MPs and peers will have to decide what happens next. It is at that moment – in late 2018 – that the real parliamentary showdown could come.

Copyright The Financial Times Limited 2017