A condition called excited delirium will likely become a new focus in the manslaughter trial of Const. Daniel Montsion as the court pieces together exactly how Abdirahman Abdi died.

It has not been proven that Abdi was in the throes of excited delirium at any point during his altercation with Ottawa police in July 2016, when Montsion punched Abdi several times in the legs and head as officers tried to handcuff him.

Regardless, his defence lawyer Michael Edelson asked hours worth of questions about the condition during his cross examination of Michael Federico, the former deputy chief of the Toronto Police Service and an expert on police use of force training Wednesday.

The condition describes someone with bizarre and aggressive behavior, paranoia and even hallucinations, according to the Mayo Clinic.

When excited delirium kicks in, patients seem stronger and seem to tire less easily than usual.

They often die when they come into conflict with police, Frederico said.

Usual techniques don't work

A police officer should ideally try to de-escalate a situation to avoid using force altogether, Federico testified, but subduing someone with excited delirium can require different tactics.

Edelson read sections aloud from a police training document, describing factors that officers should consider when confronted with someone suffering from excited delirium.

Federico agreed the first priority is to contain the person and get the person medical attention, which can be difficult to do when they are a danger to themselves and the officer.

It's complicated by the fact that usual methods of subduing a subject, like pepper spray and even blows with a baton, often have no effect on someone in that state.

Tactics can 'look very violent'

One technique includes punching or kicking the peroneal nerve in the back of the person's leg, which can temporarily cause them to lose feeling and control of that limb.

Though Federico initially said police officers are taught to avoid punching people in the head, he later agreed "distraction blows" to the face may be justified if the person is suffering from excited delirium.

He was not asked specifically about the actions of Montsion, who was wearing reinforced gloves.

Const. Daniel Montsion, right, is on trial for manslaughter, aggravated assault and assault with a weapon in the 2016 death of 37-year-old Abdirahman Abdi, left. (Supplied)

"A couple of punches may be necessary to not only get them in custody, but potentially save their life," Edelson posited.

Though the situation would look very different to a bystander, the expert agreed.

"The scene can look very violent," Federico said.

"It's not often an accurate representation of what the officers are trying to achieve."

He described the use of those techniques as "lawful but awful."

Michael Federico is a former deputy chief of the Toronto police who retired in 2017. (Craig Chivers/CBC News)

Edelson said the danger to the person and the officer would be compounded if the person had other mental illnesses.

Montsion has also pleaded not guilty to aggravated assault and assault with a weapon, along with the manslaughter charge.

Federico's testimony is expected to continue Thursday.