TORONTO - A Toronto police officer who gunned down a troubled teen on an empty streetcar four years ago says the judge overseeing his trial was wrong to exclude evidence meant to suggest the 18-year-old was trying to commit “suicide by cop.”

Const. James Forcillo is appealing his conviction and sentence in the 2013 shooting of Sammy Yatim, an incident that set off a wave of public outrage and protests.

The officer was found guilty last year of attempted murder but was acquitted of the more serious charge of second-degree murder. He was sentenced to six years behind bars, a year more than the mandatory minimum.

Recently filed documents show Forcillo plans to argue Superior Court Justice Edward Then was wrong to exclude cellphone and expert evidence about the possibility of “suicide by cop,” where a person behaves threateningly in order to trigger a lethal response from law enforcement.

His lawyers also say Then was wrong to deny an application for a mistrial once the evidence was deemed inadmissible, since that prevented the defence from countering the narrative put forward by prosecutors.

They also say Then erred in instructing jurors to view the two volleys of bullets fired by Forcillo as separate incidents, and to consider the charge of attempted murder.

Forcillo's lawyers argue that opened the door for a compromise verdict, where jurors find someone guilty of a lesser charge rather than convicting of a more serious one or acquitting them entirely.

“As a matter of common sense, the suggestion that an accused can be legally justified in killing someone but criminally liable for attempting to kill that same person within the span of less than 10 seconds in unfathomable,” they said in the documents.

“In this situation the trial judge ought to have either quashed the attempted murder count or directed the jury that if they acquitted the appellant of second-degree murder in relation to the entire transaction, they were required to similarly acquit him of attempted murder.”

Forcillo fired two volleys at Yatim, who held a small knife and was exposing himself. Court heard the first round of shots was the one that killed him.

The second-degree murder charge against the officer related to the first three shots fired, while the attempted murder charge pertained to the second volley.

Forcillo is asking the appeal court, which is set to hear his case this fall, to substitute a not-guilty verdict or order a new trial.

The officer, who is currently on bail pending the appeal, is also seeking a declaration that the mandatory minimum sentence for attempted murder is unconstitutional, and wants to be granted a suspended sentence. Barring that, he wants his sentence reduced to the minimum five years.

In the documents, his lawyers say the minimum sentence is “grossly disproportionate” and Forcillo's “moral blameworthiness in the unique circumstances of this case is at the lowest end of the spectrum.”