A British lawyer and climate campaigner was fined 5,000 pounds ($7,070) on Monday after being convicted of contempt of court for a tweet which broke an embargo on a U.K. Supreme Court judgment over Heathrow Airport’s expansion.

Tim Crosland, a director of an environmental campaign group, revealed on social media the court ruling on Heathrow Airport’s proposed third runway a day before it was made public in December. He was among involved parties to receive a draft of the appeal judgment, and has said that he broke the embargo deliberately as “an act of civil disobedience” to protest the “deep immorality of the court’s ruling.”

The court had ruled that a planned third runway at Heathrow was legal. The case was at the center of a long-running controversy and environmentalists had argued for years that the climate impact far outweighed the economic benefits of expanding the airport.

Crosland said the proposed 14 billion-pound ($19.8 billion) expansion of Heathrow, one of the world’s busiest, would breach Britain’s commitments to the Paris climate agreement.

He argued that the government “deliberately suppressed” information about the effect that the airport’s expansion would have on the climate crisis, and said the publicity gained over breaking the embargo would act as an “antidote” to that.

Addressing the court, Crosland said: “If complicity in the mass loss of life that makes the planet uninhabitable is not a crime, then nothing is a crime.”

Three Supreme Court justices found Crosland in contempt of court for his “deliberate and calculated breaches of the embargo” and fined him 5,000 pounds.

The judges said he “wanted to demonstrate his deliberate defiance of the prohibition and to bring this to the attention of as large an audience as possible.”

Crosland had brought a small suitcase to Monday’s hearing at the Royal Courts of Justice in case he was given immediate jail time. The maximum sentence had been up to two years in prison and an unlimited fine.