A British High Court has ruled that the government cannot trigger procedures to begin withdrawal from the EU without a vote by Parliament. The court rejected the government’s argument that the Crown’s prerogative powers authorize Prime Minister Theresa May to begin Brexit procedures on her own.

The government vowed to appeal to the Supreme Court. In the meantime, the court’s decision blocks May from unilaterally invoking Article 50 of the Lisbon Treaty, which begins formal withdrawal procedures from the EU, and could delay or thwart eventual Brexit negotiations.

The court reasoned that when the U.K. joined the EU, Parliament took the “major step” of passing as primary legislation the 1972 European Communities Act, which transposed EU law into domestic law, and therefore it is “not plausible” that Parliament intended that the Crown be able to unilaterally undo the Act under its prerogative power.

Key points:

  • The ruling does not overturn the results of the referendum to leave the EU and does not have any immediate effect on the immigration status of U.K. or EU nationals.
  • A vote by Parliament could block or delay Brexit procedures, which May had promised to start no later than March.
  • An appeal could be heard as early as December.

Background: The legal challenge was brought by several U.K. citizens and other interested parties, including EU nationals living in the U.K., who argued that it was unconstitutional for the government to begin withdrawal from the EU without Parliamentary assent. Under Article 50, withdrawal procedures begin when a state formally notifies the EU that it intends to leave. The notification sets off a two-year negotiations period.

The court ruling will further delay the already contentious Brexit proceedings, as European leaders have said that negotiations on the terms of a Brexit deal will not begin until the U.K. triggers Article 50.

The full court decision may be viewed here.

BAL Analysis: Although the ruling is a victory for Brexit opponents, it will be appealed and does not overturn the referendum result. If the ruling is upheld by the Supreme Court, Parliament could potentially vote against withdrawing from the EU, but many Members of Parliament recognize that the democratic consensus is to leave the EU and may instead use their vote in Parliament to gain influence over the terms of the Brexit negotiations. The expectation is that Parliamentary debate would move the government away from a “hard Brexit,” in which free movement rights are cut dramatically, toward a more nuanced relationship with the EU where benefits of the single market are secured through some sort of preferential immigration deal for EU migrants. The spike in the value of the pound immediately following the result suggests that markets have a renewed confidence in the U.K. steering toward a more business-friendly course in the eventual Brexit negotiations.

This alert has been provided by the BAL Global Practice group in the United Kingdom. For additional information, please contact

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