Oh dear. Not all so clear it after all.
The High Court in London has ruled that parliament, not the government, must approve the start of Britain's withdrawal from the European Union, in a landmark decision that could delay Brexit.
The verdict by three senior judges was closely watched around Europe and by the financial markets as it could derail British Prime Minister Theresa May's plans and affect her negotiating strategy.
Following the June referendum vote for Britain to leave the European Union, Ms May had promised to start formal exit talks by the end of March.
She claimed she had the right to use "historic prerogative powers" - a type of executive privilege - to trigger notification of Article 50 of the EU's Lisbon Treaty, which would spark two years of negotiations on Britain's departure from the bloc.
The government was to allow parliament to scrutinise the process and a vote on the final deal was likely.
"The court does not accept the argument put forward by the government," the judges said in a statement read out to the court.
"For the reasons set out in the judgment, we decide that the government does not have power ... to give notice pursuant to Article 50 for the UK to withdraw from the European Union."
Those behind the legal challenge - including an investment fund manager, a hairdresser and an expatriate living in France - had argued that Article 50 could not be triggered without a decision by parliament.
They claimed leaving the EU without such a move would remove statutory rights enshrined under the European Communities Act 1972, which made EU law part of UK law.
Ms May had accused those supporting the challenge of trying to frustrate the Brexit process, saying: "They're trying to kill it by delaying it."
The court granted the British government permission to appeal against the ruling.
A government lawyer said the Supreme Court had set aside 5-8 December to hear the matter.
British trade minister Lian Fox said "the government is disappointed by the court's judgment".
"The country voted to leave the European Union in a referendum approved by acts of parliament.
"The government is determined to respect the result of the referendum," Mr Fox told parliament.
He added: "This judgment raises important and complex matter of law and it is right that we consider it carefully before deciding how to proceed."
Last week,
Northern Ireland's High Court rejected a legal challenge to Brexit, the first judicial ruling on the issue in the UK.
The challenge rested on assumptions spiralling from the Good Friday Agreement peace accords that Northern Ireland's constitutional arrangements could only be changed with the consent of its residents.
