At 1 of Article 50,Treaty of Lisbon....
' any member state may decide to withdraw from the union in accordance with its own constitutional requirements.
Leavers are placing a lot of faith in Theresa May's use of the Royal prerogative to take us out of the EU,but the Royal prerogative has rarely tried to exercise that power and in both cases statute has exceeded prerogative...
The case of proclamations,1610... Was decided that the King by his proclamation cannot change any part of the common law or statute.
The case of fire brigades Union,1995... It would be surprising if prerogative powers could be used to frustrate the will of parliament expressed in a statute.
If a judge sought prior cases,which from my expensive experience judges often do,then the 2 cases where the Royal prerogative was exposed and competed with a statute ,the statute was deemed the higher power.
If May tries to use the Royal Prerogative it will certainly be subject to judicial review,this allows the actions of ministers,including the PM,to be challenged in the courts on the basis that the PM did not have the power to act in such a way or that the action was unreasonable or the power was exercised in a procedural unfair way,whatever the outcome of the judicial review it will also be subject to appeal.
This case ,because it questions the constitutional arrangements of the U.K.,will undoubtably be heard ultimately by our Supreme Court,don't hold your breath this could run for many years( up to 2020,hehe)
KudosDave