On June 23, 2016, the government of then Prime Minister David Cameron held a referendum on whether the UK should remain a member of the European Union. Of the 72 percent of eligible voters who cast ballots, 51.9 percent voted in favor of leaving the the EU. The unexpected outcome, which resulted in Cameron's resignation, will have a profound impact on the UK's legal system and is likely to dominate UK politics and lawmaking for years to come.
Cameron's successor, Theresa May, announced that her government would initiate the process of withdrawing from the EU by the end of March, 2017, without holding a vote in Parliament. This decision prompted a legal challenge. On November 3, 2106, a three-judge panel of the the High Court of Justice ruled that the government must obtain Parliament's consent before it can initiate the withdrawal process. The government appealed the ruling.
On January 24, 2017, the Supreme Court of the UK upheld the decision of the High Court, forcing the government to introduce a bill in Parliament authorizing the UK's withdrawal from the EU. It is unlikely that Parliament will refuse to pass the bill. Nevertheless, members of opposition parties and even some members of the governing Conservative Party, are likely to offer amendments to the bill that will place constraints on the government’s negotiating position. Other potential amendments could require Parliament to approve the withdrawal agreement or force the government to reopen negotiations with the EU if Parliament rejects the terms of the deal.
Key issues to be determined during the course of the withdrawal negotiations include whether, and to what extent, the UK will retain access to the EU's single market and whether, and to what extent, the UK will be able to curtail the free movement of EU citizens within its borders. In a speech delivered on January 18, 2017, Prime Minister May indicated that her government would prioritize immigration controls over single market access, but Parliament may amend the bill authorizing the UK's withdrawal from the EU in the hope of maintaining access to the single market.
Equally daunting are the constitutional challenges posed by Brexit. Some legal scholars contend that a general election should be held before the negotiations begin or that a second referendum will be needed to ratify the final withdrawal agreement. Most significantly, Brexit could result in the dissolution of the UK as a political entity. Nicola Sturgeon, the first minister of the devolved Scottish government, has stated that she will consider holding a second referendum on Scottish independence if Scotland's interests are harmed by the UK's departure from the EU.