Former parliamentary staffer James Ashby has dropped legal action against former speaker Peter Slipper.

Mr Ashby had alleged that while working as Mr Slipper's media adviser he was harassed through unwanted sexual advances and hundreds of suggestive text messages.

He also alleged that Mr Slipper asked him to shower with the door open in a Canberra flat.

In February, Mr Ashby won an appeal against a decision in December to throw the sexual harassment case out of court.

In a statement, Mr Ashby says he feels the decision justifies the action he took.

"The Full Court of the Federal Court not only found in my favour by awarding my appeal, but also made significant findings in my favour regarding some of the most vital aspects of my claims ... fundamentally, that the harassment had in fact occurred," he said.

Mr Ashby says he is also dropping the case because of increasing costs in what he describes as "deep pocket" litigation.

"Confirmation of by the Minister of State, Michael Ronaldson, that Mr Slipper will continue to have taxpayer support for an unknown 'quantum' in funding makes this case financially very one-sided," he said.

"This gross imbalance in funding makes it unpredictable how long this case may run, and more importantly cost.

"This type of 'deep pocket' litigation, where one side has unlimited money, from the taxpayers, makes it fundamentally unfair for an ordinary person seeking justice."

In his statement, Mr Ashby also cited reports that Mr Slipper has been "mentally unwell" as a further consideration in his decision.

"Under such circumstances, I do not wish to continue lengthy proceedings that could potentially cause him great harm," Mr Ashby said.

Mr Slipper has previously called for a royal commission into the circumstances surrounding the case.

The 64-year-old controversially defected from the Coalition in 2011 to take up the position of speaker under the then-Labor government.