OTTAWA -- Canada's chief military judge took the witness box during his own court martial on Tuesday, testifying about his personal and professional relationship with his deputy -- who is also the presiding judge for his trial.

The surreal scene was the latest twist in an unprecedented legal case, in which Col. Mario Dutil is being tried on eight charges in the very military-court system he has served as the top judge since 2006.

The charges relate to allegations he had a consensual but inappropriate relationship with another subordinate and knowingly signed a travel claim for $927.60 that contained false information.

He is facing two counts of fraud, one of wilfully making a false entry in an official document, one of wilfully making a false statement in an official document, and four related to conduct or neglect to the prejudice of good order and discipline. Dutil has denied any wrongdoing.

A special committee of three judges dismissed a complaint about the relationship with the other subordinate in April 2016, saying it did not have any impact on his work.

The relationship between Dutil and deputy chief military judge Louis-Vincent d'Auteuil has figured prominently in the first two days of the court martial thanks to a motion for d'Auteuil to recuse himself from the case.

That motion was brought forward not by military prosecutors but Dutil's own lawyer, Philippe-Luc-Boutin, who asked d'Auteuil to step away, saying the judge is too intertwined in the case involving his colleague on the military's five-judge bench.

The prosecutors say they have confidence in d'Auteuil's ability to preside over the case in an impartial manner -- and that contrary to Boutin's suggestions, the civilian system should not handle the matter.

Wearing a blue suit and sitting only metres away from d'Auteuil, who was dressed in his black judge's robe with a red sash, Dutil described how the two military judges developed a close friendship after years working together.

"Over time, Judge d'Auteuil became my confidant," Dutil said at one point in French in response to a question from Boutin, later adding: "Judge d'Auteuil is my closest colleague."

Dutil acknowledged during his testimony that the two judges grew more distant following allegations about the relationship and travel claim, when he delegated much of his authority to d'Auteuil.

"We changed things," said Dutil, whose demeanour shifted from combative to introspective and back through much of Tuesday's testimony. "I kept a certain distance ... We communicated, obviously. Life continued."

The two judges nonetheless spoke about the complaint, Dutil said, adding d'Auteuil knew many of the facts of the case.

Boutin even served a subpoena on d'Auteuil shortly after the court martial commenced Monday, which in theory would mean the judge could end up presiding over the trial and testifying from the witness box.

"Judge d'Auteuil is an essential witness in this case," Dutil said. "On the facts, but also on the dynamic, the complexity, the context of this file. And everything that happened after the investigation, and all the actions that followed."

Dutil later spoke of his relationships with the military's three other judges, including one with whom he does not get along.

Despite this, military prosecutor 2nd Lt. Cimon Senecal told The Canadian Press after the day's proceedings that he remains confident in d'Auteuil's ability to preside over the case in an impartial manner.

"We believe that Judge d'Auteuil, when he was appointed as a judge, he made his oath of office and he's subject to the oath of office to be impartial," Senecal said.

"We believe that with this presumption of impartiality and with these safeguards -- the fact that it's public, it's recorded and subject to appeal -- we are confident Judge d'Auteuil is in a position to make a fair decision without bias."