Const. James Forcillo, the Toronto police officer convicted in the streetcar shooting death of teenager Sammy Yatim, was in court Wednesday for the first day of his sentencing hearing, with his lawyers arguing that the mandatory minimum five-year sentence for attempted murder is unconstitutional and should not apply to an officer on duty.

The Crown is seeking an eight to 10-year sentence for Forcillo, who was convicted of attempted murder in January following a lengthy trial. Forcillo has been free on bail since the verdict.

In a written argument submitted to court Wednesday, Forcillo's defence team said that the officer's "moral culpability is at the lowest end of the scale for attempted murder."

"Unlike in almost all other attempt murder cases, Officer Forcillo believed that he was acting in accordance with the law at all times during the encounter."

Forcillo does not present any harm to the community, the defence went on.

Defence lawyer Lawrence Gridin suggested that a grossly disproportionate sentence would amount to cruel and unusual punishment. If the judge finds that the appropriate sentence for Forcillo is below the minimum, then the law is unconstitutional, Gridin said.

At issue, he said, is the fact that a firearm was used in this case. Attempted murder without a gun doesn't have a mandatory minimum, Gridin said.

Justice Edward Then disputed that, saying the use of a firearm isn't the only factor that affects the mandatory minimum. The officer's intent is also a factor, Then said.

Gridin conceded that a five-year minimum for attempted murder with a gun is not extreme, but that there were exceptions.

Court is adjourned for the day.

Officer 'duty bound to respond'

Earlier Wednesday, Forcillo's other lawyer, Peter Brauti, argued that the five-year sentence that comes with a conviction for attempted murder was created as a deterrent for criminals, not police officers on duty with an obligation to protect the public.

"As a normal citizen I don't have duty to engage Mr. Yatim," Brauti argued in court Wednesday morning. "But the officer doesn't. He is duty-bound to respond when an officer is placed in those circumstances that's when the courts view it as a mitigating factor."

Brauti said Forcillo's actions amount to a case of "excessive self-defence" though he was challenged on this point by Justice Then, who pointed out that self-defence was disproved by the Crown and that a jury found him guilty of attempted murder.

Yatim, 18, was high on drugs and brandishing a small knife on the streetcar when he was shot by Forcillo.

Forcillo faced two charges related to Yatim's death in July 2013, but was found not-guilty of second-degree murder.

The jury believed Forcillo was justified in firing the first three shots at Yatim, but not the second round of shots, and found him guilty of attempted murder.