| LONDON
The government, which had planned to start the EU divorce without going through parliament, said it would appeal against the ruling and the Supreme Court has set aside Dec. 5-8 to hear the case.
The stage is now set for a period of political uncertainty while ministers digest the ruling and how to respond to it.
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HOW DID THE GOVERNMENT REACT?
"The government is disappointed by the court's judgment," trade minister Liam Fox said on Thursday.
"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," he told parliament.
WHAT ARE THE GOVERNMENT'S OPTIONS?
Legal commentators say ministers now have two basic options: a simple vote in parliament on whether to trigger Article 50 or a new bill granting the right to leave the EU, which will have to be debated by lawmakers.
WHAT WOULD A NEW BILL ENTAIL?
David Pannick, the lawyer for the lead claimant, said parliament could approve such a bill, reject it or pass it with amendments on details such as the date of notification.
The best case for the government would be to avoid legislation and involve parliament through a so-called substantive motion -- a proposal put forward for debate and a vote. This would be a quicker process and could be done early next year.
Legislation would take longer as it involves various stages of debate and approval. It can also be held up by so-called "ping pong", whereby a bill goes back and forth between the lower and upper house of parliament, being amended and voted on.
HOW LONG WILL ALL THIS TAKE?
While it is possible legislation could be introduced and passed between the time of a final judgment late this year, and May's end-of-March 2017 deadline, it is likely to be tight and may result in the triggering being pushed back.
The 1972 European Communities bill, which set the terms of Britain's entry into the European club, involved a total of about 40 days of debate during its passage through parliament, according to the Institute for Government.
COULD PARLIAMENT BLOCK BREXIT?
Lawmakers in the lower house, the House of Commons, are thought to be unlikely to try to stop Brexit, and a Reuters survey suggested many who voted to "remain" would now vote to trigger Article 50 in a parliamentary vote.
However, a cross-party group of lawmakers, who support a "soft Brexit", whereby Britain stays in or remains close to the EU single market, have demanded a greater say for parliament in negotiations and say they might try to pass amendments that guarantee this.
The government may also face trouble in the House of Lords, where the ruling Conservatives do not have a majority. If the Lords were to block the bill the government could decide to overrule it using the Parliament Act, although it cannot re-table the bill until the next parliamentary session.
The new parliamentary session usually starts in May or June, so that would delay the Brexit process significantly.
http://uk.reuters.com/article/uk-britain-eu-article50-factbox-idUKKBN12Y1GH?mod=related&channelName=domesticNews
