Crown lawyers acting for the United States knew before seizing Kim Dotcom's fortune and property that they were using an unlawful court order.
The High Court file has revealed Crown prosecutor Anne Toohey realised there was a paperwork problem on the morning of the January raid.
The Solicitor-General at the time, David Collins, was alerted to the error but told the mistake didn't alter the lawful nature of the order allowing the seizure of Dotcom's wealth.
The advice was wrong - Justice Judith Potter later ruled the restraining order "null and void" and having "no legal effect".
The result left Dotcom without the chance to have his day in court or the money to fund a fight against claims he was behind as international criminal conspiracy in copyright infringement.