Former Liberal staffer Bruce Lehrmann has lodged two defamation cases, one against the Ten Network and the other against News Life Media in the Federal Court, over coverage of allegations he raped Brittany Higgins.

Mr Lehrmann's trial was abandoned last year after a juror's misconduct and prosecutors dropped the charge when they decided not to proceed with a retrial, after fears for Ms Higgins's health.

Mr Lehrmann has always maintained his innocence and there have been no findings against him.

The defamation action was foreshadowed in December when he retained Sydney lawyer Mark O'Brien.

Mr O'Brien said Mr Lehrmann had been considering potential defamation proceedings over public statements, broadcasts, articles and social media posts.

No details about the two claims have been released, but three documents have been filed in each case including an originating application and a statement of claim.

No mention or hearing dates have been listed.

Under new Federal Court rules details in documents handed to the court won't be made public until the initial mention or hearing.

Mr Lehrmann has lodged several complaints with official bodies already, including a complaint to police about a statement Ms Higgins made outside the court on the date the trial ended.

He also lodged a formal complaint against the ACT's Director of Public Prosecutions Shane Drumgold to the ACT Bar Association.

The Federal Court action comes as an inquiry is about to begin into allegations from Mr Drumgold that police tried to pressure him to not press the charge against Mr Lehrmann.

The allegations were made in a letter to police.

The Board of Inquiry will be run by former Queensland Judge and Solicitor General Walter Sofronoff.