The European Court of Justice will at the end of this month begin hearing a legal challenge brought by anti-Brexit campaigners to force the government to spell out how Britain could revoke its notice to leave the EU.
The hearing comes after the British government was refused permission Tuesday to appeal to the UK Supreme Court over the case, amid growing calls for Prime Minister Theresa May to hold a second referendum on Brexit.
"The best, the really compelling, the objective evidence that all options are still on the table is the desperation with which the government acted to try and block MPs from seeing the clear path to remain," said Jolyon Maugham, a lawyer who has spearheaded the legal challenge.
The Supreme Court rejected a bid from the government for permission to appeal against a lower court ruling asking the European Court to spell out "whether, when and how" Britain can unilaterally revoke its notice to leave the EU, which would see the UK pull out on March 29.
Labour, Scottish nationalist and Green members of the British, Scottish and European parliaments brought the case through the highest civil court in Scotland.
The Court of Session in Edinburgh ruled in September to refer the question to the Court of Justice of the EU.
A hearing at the Court of Justice of the European Union (CJEU) is set for November 27.
The British government applied to the Court of Session for permission to appeal against the ruling to the higher UK-wide Supreme Court, but the application was rejected.
The government then applied directly to the Supreme Court itself for permission to appeal.
But in refusing that permission on Tuesday, the Supreme Court said the Court of Session's ruling was "preliminary" and the Scottish court would still have to reach a judgement of its own after receiving the CJEU's guidance.
Britain invoked Article 50, its two-year notice of intention to withdraw from the EU, in March 2017.