So what is Article 50? Article 50 states: "Any Member State may decide to withdraw from the Union in accordance with its own constitutional requirements. Story highlights Article 50 of Lisbon Treaty paves way for formal negotiations between EU and BritainOnce invoked, agreement on UK-EU relations has two-year deadline(CNN) British voters opted out of the European Union in last year`s historic referendum, but Brexit can`t actually get underway until Article 50 of the Lisbon Treaty is triggered. Within the Lisbon Treaty lies a 250-word, five-point framework, which outlines voluntary departure from the European Union. "The article specifies that the exiting state must notify the European Council of its intent so formal negotiations for a withdrawal agreement can begin.

What the court saidThe Supreme Court judges voted eight to three against the government, upholding a November High Court decision. London (CNN) Britain`s Supreme Court has ruled that the UK government must hold a vote in parliament before beginning the process of leaving the European Union. May took over the premiership after former leader David Cameron stood down over the Brexit vote. "To proceed otherwise would be a breach of settled constitutional principles stretching back many centuries," Lord David Neuberger, president of the Supreme Court, said as he read out the ruling. "The British people voted to leave the EU, and the government will deliver on their verdict -- triggering Article 50, as planned, by the end of March.