Officials from the National Anti-Corruption Commission searched the 31-year-old's home in June 2024 over allegations he misappropriated secret documents related to French submarines five years earlier.
The anti-corruption body was searching for sensitive documents on the since-abandoned submarine project Lehrmann was alleged to have stolen from the office of former defence minister Linda Reynolds.
He has denied the claims and has sought assistance from the federal government to cover his legal costs of the investigation.
Senator Reynolds' former staffer is seeking to expand a Federal Court lawsuit against federal Special Minister of State Don Farrell and NACC Commissioner Paul Brereton.
His new allegations, revealed by the court on Tuesday, include a two-day secret hearing forcing him to give evidence in October 2024 in Hobart was unlawful.
"The hearings were conducted unlawfully, without any compliance with rules of evidence, procedural fairness or natural justice," he wrote.
He criticised a non-disclosure notation gagging him from speaking about the hearings and said he had not been given transcripts despite being promised them.
Lehrmann has expanded his claims over the June 2024 raids - where two personal diaries were seized - saying they were conducted in excess of the corruption watchdog's power.
The 31-year-old also alleges the commission breached its non-publication orders by revealing his name and travel details when booking plane tickets and hotel accommodation in September 2024 for separate hearings in Sydney.
He will fight to bring these additional claims against Mr Farrell and Mr Brereton at a hearing on October 15.
At that time, he will seek court orders halting any inquiries, investigations or proceedings brought against him by the anti-corruption commission.
Lehrmann claims the probe was spurred by "frivolous, James Bond-like allegations".
He is accused of gathering the confidential information in March 2019, days after he allegedly raped his colleague Brittany Higgins in Senator Reynolds' office at Parliament House.
He has denied the sexual assault claims, which remain untested in a criminal court after a 2022 trial in the ACT was abandoned because of juror misconduct.
But Federal Court Justice Michael Lee found in 2024 the allegations he raped Ms Higgins were proven on the balance of probabilities and dismissed his defamation suit against Network Ten and presenter Lisa Wilkinson.
That finding was upheld twice by the Full Federal Court and the High Court.
