What does UK ruling mean for Brexit and what comes next?

London - Britain’s Supreme Court has ruled that Prime Minister Theresa May needs an act of Parliament to trigger Article 50 of the Lisbon Treaty to begin negotiating the UK's departure from the European Union. How exactly will the parliamentary procedure work and what does that mean for Brexit?

What did the Supreme Court demand?

The judges decided 8-3 that an act of Parliament is needed. That means May has to present a bill, which can be amended, and which has to go through both chambers of Parliament, including the unelected House of Lords.

How long would the process take?

In theory, bills can complete the entire parliamentary process in a single day. But that’s only happened in emergencies and where there’s cross-party agreement. It more usually take weeks - or months.

There are a series of stages in each chamber, with votes at each stage, and lots of opportunities for dissenters to propose amendments. Both houses must agree on the wording of the final law.

Will Parliament block Article 50?

Almost certainly not. The referendum result makes it hard for lawmakers to vote against leaving the EU. Most of May’s Conservative Party now supports exit, and the opposition Labour Party has said it won’t block Article 50 - though individual lawmakers may rebel. The unelected Lords will likewise be reluctant to defy the will of the people as expressed in the referendum.

What will Brexit opponents do, then?

They can put roadblocks in the government’s way, adding amendments to the legislation. May’s Commons majority is small. Most members campaigned against Brexit, and many have reservations about the flavour of the divorce that May is going for. If someone can find the right amendment, he or she could well carry the chamber.

Who can put forward an amendment?

Any member of Parliament, but Speaker John Bercow decides which ones get debated. Already, the main opposition Labour Party, which has 229 lawmakers in the 650-member House of Commons, has said it’ll seek to amend any Article 50 bill. The Scottish National Party, which has 54 MPs, has promised to submit 50 “serious and substantive” amendments. Plaid Cymru of Wales, which has three lawmakers, has also said it’ll try to amend the bill. The sole Green Party lawmaker, Caroline Lucas, said she’ll oppose the bill and the Liberal Democrats, with nine MPs, said they’ll oppose it unless it guarantees a referendum on the eventual outcome of the Brexit negotiations.

What might the dissenters ask for?

They’re likely to go for options that bind the government’s hands and highlight the problems as the Brexit talks proceed. Requirements for regular parliamentary updates on the progress of negotiations would mean ministers having to face repeated questioning on their strategy, and possibly repeated embarrassment if things aren’t going well.

Labour will seek to keep “full, tariff-free access to the single market” and make sure the government remains accountable to Parliament throughout the process. The Liberal Democrats, who have nine lawmakers out of 350, will vote against triggering Brexit without a commitment that the final deal goes to another referendum.

A requirement to hold a second referendum on the outcome of the negotiations would see a repeat of the 2016 plebiscite: but this time voters would have to choose with a precise alternative to EU membership on the table. It remains moot, though, under what terms the EU would have the UK back once the triggering of Article 50 had set the clock ticking on the two-year exit countdown.

The SNP said its 50 planned amendments will include a call for the government to publish a formal white paper outlining planned future legislation before triggering formal talks.

So what does this mean for Brexit?

As Theresa May is fond of saying, “Brexit means Brexit.” The ruling doesn’t change that, but it does make it harder for May and her team to push ahead with their vision of a so-called hard Brexit. It may also slow the process down and give other parties a greater say.