Europe

Britain's Brexit bill receives royal assent, becomes law

  • A European and British Union flags hang outside Europe House, the European Parliament's British offices, in London, Tuesday, March 14, 2017. (AP Photo/Matt Dunham)

    A European and British Union flags hang outside Europe House, the European Parliament's British offices, in London, Tuesday, March 14, 2017. (AP Photo/Matt Dunham)  (The Associated Press)

  • British Prime Minister Theresa May leaves 10 Downing Street in London, to attend Prime Minister's Questions at the Houses of Parliament, Wednesday, March 15, 2017. (AP Photo/Matt Dunham)

    British Prime Minister Theresa May leaves 10 Downing Street in London, to attend Prime Minister's Questions at the Houses of Parliament, Wednesday, March 15, 2017. (AP Photo/Matt Dunham)  (The Associated Press)

  • Scottish First Minister Nicola Sturgeon smiles during a Scottish Government cabinet meeting in Bute House, Edinburgh, Scotland Tuesday March 14, 2017.  Sturgeon announced on Monday plans for a fresh referendum on Scottish independence before Britain finally leaves the EU. (Jane Barlow/PA via AP)

    Scottish First Minister Nicola Sturgeon smiles during a Scottish Government cabinet meeting in Bute House, Edinburgh, Scotland Tuesday March 14, 2017. Sturgeon announced on Monday plans for a fresh referendum on Scottish independence before Britain finally leaves the EU. (Jane Barlow/PA via AP)  (The Associated Press)

A bill authorizing Britain to start its exit from the European Union has received royal assent and is now law.

House of Commons Speaker John Bercow announced Thursday that the European Union (Notification of Withdrawal) Bill has received the assent of Queen Elizabeth II.

The bill was passed by Parliament on Monday.

Royal assent is a formality — no monarch has refused to sign a bill for more than 300 years

It means that Prime Minister Theresa May is now free to invoke Article 50 of the EU's key treaty, triggering two years of exit negotiations. She says she will do that by March 31.