The decision comes as a major blow to Queensland police whistleblower Rick Flori's bullying case against his former employer, with his complaint about sexual conduct between two officers not affording him public interest disclosure protection.

The former Gold Coast sergeant claimed he suffered reprisal after sending a letter to the then-Crime and Misconduct Commission alleging in late 2009, a female police officer performed a sex act on a male colleague in a police car at a Red Rooster car park.

In the letter, Mr Flori expresses concern about "special attention" given to the female officer.

"It was obvious that (the female officer) had her head in (the male officer's) lap giving him a head job," he wrote in February 2010.

"I can see the headline. Senior police officer receives fellatio in police car."

Mr Flori has argued he should have been protected under the Whistleblowers Protection Act, which states a public officer may make a public interest disclosure about someone else's conduct if it is "official misconduct".

He is suing three officers - David Brett Winter, Peter Doyle and Dirk Peterson - as well as the Queensland government, for reprisal in Brisbane Supreme Court.

But Justice Helen Bowskill said he was not afforded whistleblower protection so his case regarding the letter cannot proceed.

"Such conduct may amount to 'police misconduct'," she said.

"The fact they are sitting in a police car, and using the car for a reason unrelated to their professional duties at the time of the sexual act, is not sufficient, in my view, to raise 'misconduct' to the level of 'official misconduct'.

"The letter is not capable of being a public interest disclosure under ... the Whistleblowers Protection Act."

Mr Flori quit the force before being acquitted by a jury of misconduct last year after leaking footage of police bashing a handcuffed man in a police station basement in 2012.

Prosecutors alleged he leaked the footage as part of a vendetta against Senior Sergeant David Joachim, an officer involved in the arrest who was also promoted ahead of him.

Australian Associated Press