The attorney general has begun an investigation into the barrister who broke the embargo on the Supreme Court’s ruling on Heathrow Airport last month.

Tim Crosland, a barrister and director of eco-charity Plan B Earth, has seven days to provide representations to law officers in the attorney general’s office. Plan B Earth is also being investigated for contempt of court.

Crosland, who represented Plan B Earth in Heathrow’s Supreme Court appeal, said he leaked the judgment about the third runway as an act of ‘civil disobedience’. If found to be in contempt of court, he could be sent to prison for up to two years.

Speaking to the Gazette, Crosland said he did not regret his decision to break the embargo and said he was confident he would be prosecuted.

‘You have a short window for journalists to think about the outcome of a court case. It’s only newsworthy for that 24 hours… My assessment was that if I waited for the judgment to be out and then say “this is really dishonest” no one would have paid any attention. It wouldn’t have been noticed,’ he said.

Crosland claims the judgment - which found that the government’s decision to approve a third runway at Heathrow was made lawfully with reference to climate targets - misleads the public about the safety of the expansion plans.

A spokesperson for the attorney general’s office said: ‘AGO officials are currently seeking representations following the Supreme Court’s referral. No decision has yet been made, and it would not be appropriate to comment further at this stage.’