A judge has sided with Const. Daniel Montsion, agreeing to hear his defence team's request to halt the Ottawa police officer's manslaughter trial based on allegations of negligence by Ontario's Special Investigations Unit (SIU).

Montsion has pleaded not guilty to manslaughter, aggravated assault and assault with a weapon in the 2016 death of Abdirahman Abdi.

The officer's defence team has asked for the charges to be dismissed, or to have key video evidence thrown out.

The defence alleges the SIU was negligent in its handling of the surveillance video, infringing on Montsion's charter rights.

The Crown attempted to convince the judge to quash the request, but Justice Robert Kelly ultimately decided to give the defence a chance to prove its claims about the SIU investigation.

"I am satisfied the defence has identified a basis in fact and law on which its proposed charter application could succeed," Kelly said Tuesday.

That means there will essentially be two trials going on at once: Witnesses will be called to testify both about Montsion's actions during Abdi's arrest, and about the handling and content of the surveillance video.

The judge will decide whether Montsion's rights were violated and whether the charges against him should be stayed after he hears more evidence.