08:31

The UK supreme court won’t deliver its judgement whether the Scottish and Welsh government’s emergency Brexit legislation breaches the law until after MPs stage their crucial vote on May’s deal next week.

The supreme court announced it would hand down its decision on the so-called “continuity bills” passed by the devolved legislatures on Thursday 13 December, effectively leaving MPs in the dark on whether those bills were legally valid or not when they decide whether to back Brexit or not next Tuesday. It heard the legal challenge by the UK government in July.

By contrast the European court of justice will issue its judgement on 10 December, only two weeks after holding an emergency hearing on whether article 50 could be unilaterally revoked, in a case brought by a cross-party group of Scottish parliamentarians.

The UK, Scottish and Welsh governments are at loggerheads over whether the devolved legislation is permissible, because it gives both legislatures legal powers over repatriating EU legislation.

The UK government insists that is ultra vires, since foreign treaties are reserved to Westminster; Nicola Sturgeon, the Scottish first minister, and her former Welsh counterpart, Carwyn Jones, accused UK ministers of a “power grab” for taking control of some policy areas.