Parliament is sovereign

Parliament is sovereign, and that's what we voted for.

Parliament must vote on whether the UK can start the process of leaving the EU, the High Court has ruled. This means the government cannot trigger Article 50 of the Lisbon Treaty - beginning formal exit negotiations with the EU - on its own. Theresa May says the referendum - and existing ministerial powers - mean MPs do not need to vote, but campaigners called this unconstitutional. The government is appealing, with a further hearing expected next month.

It is a fundamental principle of the UK constitution that Kings' or Queens' powers cannot be used by the government via the Royal Prerogative to change or do away with rights under British law unless Parliament gives it authority to do so. The court looked at examples ranging from the 1600s to the 1970s Laker Airways legal battle.

http://www.bbc.co.uk/news/uk-politics-37857785