>> The final day of a major Brexit showdown over who has the power to kick off the divorce. Lawyers arriving at the Supreme Court on Thursday. The government argues it can trigger article 50 unilaterally. But the High Court last month ruled MP should get a vote. The decision's now gone to the very top with 11 justices considering the case this week.
And as Reuters Carly Mclennan reports, the government's already preparing for a potential loss.>> If it loses the appeal, it will have to introduce a bill to Parliament giving MPs a vote on triggering article 50. It's being reported they've already prepared that bill in anticipation. And that they've prepared a very short, three-line bill that they think would be very difficult for MPs to try and amend and add conditions to.
>> Research by Reuters suggests Prime Minister Theresa May would have the numbers to pass such a bill. Which has some questioning why the government is bothering with the appeal.>> Some have argued it could be a delaying tactic on the part of the government to give it more time to prepare for negotiations.
But it's likely that it's just a point of principle. Theresa May believes that she has the power to trigger article 50 without Parliament's approval, and she wants to go ahead and do that.>> The European Union.>> May has filed to begin proceedings by the end of March.
On Wednesday, MPs backed that time table, along with an agreement that the government will first lay out its negotiating plan.