Chris

An Act of primary legislation sufficient to authorise the repeal of the European Communities Act 1972.

The court case hinged on whether the government could use its ancient powers of royal prerogative to invoke Article 50 of the Treaty of Lisbon. The government argued that invoking A50 did not impinge upon the sovereignty of Parliament because the act of invocation did not create or repeal any law. The High Court has ruled that, because A50 sets out a timetable that leads inevitably to the UK leaving the EU, the act of invocation effectively does put the government in the position of repealing a law passed by parliament. The government cannot do that; a long and bloody civil war was fought in these islands in the 17th century over that issue. Parliament is sovereign. Only it can make and repeal laws.

While they are preparing their appeal to the Supreme Court, they will also now be trying to work out just how little they can get away with. They won't want to put their Great Repeal Act forward yet, it will take many months to draft it. May says she still wants to invoke A50 by the end of March. I suspect she will go for a bare-bones Act which enshrines the referendum result in law (can't help wondering whether Cameron's failure to do that was a cunning little trap door, just in case), grants executive power to repeal the ECA 1972 and compels the government to put something in its place by a certain date.