Sergeant Brett Coutts is suing retired colleague Scott Walls for defamation in the ACT Civil and Administrative Tribunal after Mr Walls posted a comment on another former officer's Facebook page in February 2018.

The post related to an incident at the former Cabinet nightclub in Manuka in May 2012, in which Mr Coutts used capsicum spray on a man who allegedly indecently assaulted a woman in the womens' toilets, and used physical force during the subsequent arrest. The incident was captured on surveillance footage.

Mr Coutts and Mr Walls were working together that night.

Following the incident, Mr Walls filed a complaint against Mr Coutts for the alleged use of excessive force and Mr Coutts was suspended from work.

Professional standards investigated the matter, with a conclusion by a panel member that the excessive force complaint had been made out.

The-then Assistant Commissioner Leanne Close in 2013 decided Mr Coutts' employment should be terminated.

Mr Coutts applied for judicial review of the decision to terminate his employment, but the Federal Court in 2014 dismissed his application.

The AFP decided in the end not to sack the sergeant.

In a statement of claim lodged with the tribunal by solicitor David Healey, Mr Coutts argues Mr Walls' Facebook comment carries a number of defamatory imputations, including that he is a "thug", that he is a criminal with a history of convictions for assault, that he is unfit to be a police officer, and has been somehow protected from the AFP from dismissal.

Mr Coutts claims general damages to the tune of $25,000 and seeks an order forcing Mr Walls to publicly apologise with a notice in The Canberra Times.

"The comments on the Facebook article have caused the applicant to suffer a loss of standing in the eyes of his AFP colleagues, his family, friends and the community generally," the statement of claim says.

However, Mr Walls, who served as a sworn officer in the AFP for 27 years, intends to defend his commentary.

He is seeking to have the defamation proceedings removed from the ACAT to the ACT Supreme Court, and potentially call some high-powered AFP witnesses.

Two barristers, including high-profile silk Stuart Littlemore QC, have been briefed on the case.

Documents filed with the tribunal by Mr Walls' lawyer, Aulich Law's Stefan Russell-Uren, say Mr Walls denies the alleged imputations arise from the post.

However, the documents say he is likely to rely on various defences to defamation including justification under statute and at common law, contextual truth, qualified privilege, fair comment and honest opinion, as well as bad reputation and triviality.

He has not yet filed a defence, citing inadequacies in the statement of claim.

The two men are previous ACT Policing team members and colleagues.

They worked the Canberra streets in the former Beats and patrol teams on overnight shifts where contact with abusive, difficult and often alcohol-affected members of the public was a regular occurrence in and around the city's nightclub precincts.

In the tribunal last week, Mr Walls asked for the case to be removed to the Supreme Court on the basis that defamation is a complex matter requiring specialist and costly legal advice.

He says the questions of law and fact are highly complex and warrant the attention of a superior court.

He also points to mounting legal costs in relation to the matter, which will quickly exceed the $25,000 maximum in damages that can be paid in the tribunal's jurisdiction.

In addition, costs cannot be awarded to successful parties in the tribunal.

Mr Russell-Uren has also flagged the need for written evidence, surveillance camera footage and to subpoena witnesses.

Witnesses would likely include a number of serving and retired senior AFP officers.

The application to remove the case was resisted by Mr Coutts.

The statement of claim also says Mr Walls was given the opportunity to retract the allegations but declined to do so.

Mr Walls is no longer with the AFP, having suffered post traumatic stress and retiring in April 2017.

Mr Coutts remains a serving officer.

The tribunal member who heard the application to remove the case to the ACT Supreme Court has reserved his decision.