A High Court ruling that the government must give MPs a vote on triggering Article 50, the official mechanism to split from the EU, is "reasonable", according to a co-architect of the Vote Leave campaign.
Dominic Cummings urged fellow Eurosceptics to ignore some "bad bits" in the judgement and focus on the fact that the executive cannot overrule parliamentary sovereignty on domestic law.
"Triggering [Article] 50 without parliamentary approval [would] breach this principle [because it would] create a situation in which the [European Communities Act 1972] must be repealed," he told his Twitter followers.
"Judicial activism is [a] big problem, but that is not the point today — we won to make UK a serious country, this is [more] important than tactics."
Cummings' comments are in stark contract to warnings from Nigel Farage and Leave.EU co-founder Arron Banks.
"I now fear that every attempt will be made to block or delay the triggering of Article 50. If this is so, they have no idea of the level of public anger they will provoke," the interim Ukip leader said.
Insurance businessman Banks, meanwhile, claimed the three judges had declared war on British democracy. "It's no surprise that the legal establishment has joined the political class in declaring war on British democracy," he said.
"Why wouldn't unelected judges want to preserve an EU system where unelected elites like themselves are all-powerful?
"I don't think the people are going to take this lying down. Leave.EU will now be going back into full campaigning mode, and I would urge anyone who believes is democracy to sign up and join the fight."
Theresa May had promised to trigger Article 50 before March 2017, starting two years' worth of Brexit negotiations with Brussels.
But the government will now appeal the High Court decision at the Supreme Court sometime in December. A full response to the ruling from the Conservative administration is expected on 8 November.
How the government reacted
"The government is disappointed by the Court's judgment. The country voted to leave the European Union in a referendum approved by Act of Parliament. And the government is determined to respect the result of the referendum. We will appeal this judgment."