London: Britain's Supreme Court will Monday begin hearing the government's appeal against a ruling it must obtain parliamentary approval before triggering Brexit, in a constitutional showdown that has further inflamed political tensions.
The High Court dramatically ruled last month that Prime Minister Theresa May's government did not have the power to invoke Article 50 of the European Union's Lisbon Treaty, the formal procedure for leaving the EU.
The judgement prompted fury amongst Brexit supporters who fear that lawmakers, who are overwhelmingly in favour of staying in the EU, may seek to delay or soften Britain's withdrawal.
They have warned of a potential "constitutional crisis" as the judges rule on the limits of executive power. Following a heated and divisive campaign, Britons voted by 52 per cent to leave the EU in the June 23 referendum.
But the act legislating the vote did not make the result legally-binding, meaning either the government or parliament still has to pull the trigger.
In the shadow of the Houses of Parliament, all 11 Supreme Court judges will on Monday begin four days of appeal hearings, with a decision due in January.
Despite the complexity of the issues involved, they will be under pressure to make a swift ruling, as May has promised EU leaders she will invoke Article 50 by the end of March.
May argues that as head of the government she has constitutional authority over foreign affairs, including the right to withdraw from treaties, under so-called "royal prerogative" powers.
But the claimants in the case, led by investment fund manager Gina Miller, counter that Brexit would nullify some domestic laws and strip citizens of certain rights — actions that only parliament can carry out.
The High Court ruling against the government was cheered by opponents of Brexit, who hope that pro-European lawmakers may be able to use a parliamentary vote to ease the terms of the divorce, for example by keeping Britain in the single market.
But the decision prompted personal attacks on the judges from members of May's Conservative party and in the eurosceptic media, with one tabloid calling them "Enemies of the People".
An added complication in next week's hearings will be the presence of representatives from the devolved Scottish and Welsh governments, who are expected to argue that Article 50 also needs to be approved by their devolved parliaments.
Such a ruling could derail May's timetable further and, given that Scottish lawmakers are opposed to leaving the EU, set up a stand-off between the nations.
