The Australian Federal Police (AFP) acted unlawfully when by raiding the Canberra headquarters of the Construction, Mining, Forestry, and Energy Union (CFMEU), the ACT Supreme Court has found.

AFP raided the CFMEU’s Dickson offices in August this year so that detectives attached to the Royal Commission into Trade Union Governance and Corruption could seize materials.

The union sued AFP for the unlawful intrusion.

Union lawyers argued in court that much of the seized material, which was obtained under two separate warrants, had nothing to do with the royal commission’s investigations.

The union also claimed officers began their search without producing a warrant, and that union officials were kept away from certain rooms during the raid.

Supreme Court Justice Richard Resfshauge has ruled that the conditions of the search warrant had been ignored.

He ordered AFP to return most of the seized materials, and destroy its copies.

Police will still get to look at some of what they took under one of the warrants, but there is a good chance it will be challenged if they want to use it as evidence in court.

The AFP has been ordered to pay costs as well.