Robert Latimer is applying to Prime Minister Justin Trudeau and Justice Minister Jody Wilson-Raybould for either a pardon or a new trial for the killing of his daughter in 1993.

Latimer killed his severely disabled 12-year-old daughter, Tracy, in 1993 by piping exhaust fumes into the cab of his truck.

In an application filed on Wednesday, Latimer's lawyer claims the circumstances of his client's 1997 conviction amount to the kind of miscarriage of justice that deserves a rare ministerial review.

Failing that, Vancouver lawyer Jason Gratl says Latimer deserves a pardon.

"Granting a pardon to Mr. Latimer does not detract from any value or principle and offers Canadians the rarest of mirrors through which to appreciate the meaning of our collective association," Gratl wrote in a letter accompanying the application.

"A pardon would offer a glimpse of mercy, compassion and justice that the legal system and the medical system did not afford to the Latimers."

'Compassionate homicide'

Latimer's case has already proven one of the most polarizing in Canadian legal history.

He has appeared twice before the Supreme Court of Canada — first in 1997 when the court ordered a new trial due to jury interference and a second time in 2001, when the court upheld a life sentence with no parole for 10 years.

An undated photo of Latimer and his daughter Tracy at home. Latimer admitted to killing Tracy in 1993 by piping exhaust fumes into the cab of his truck. (Maclean's/Canadian Press)

Latimer told police he did it — he said he loved his daughter, who had a severe form of cerebral palsy and was thought to be in chronic pain, and couldn't bear watching her suffer.

The case has divided supporters who believe the case is one of so-called mercy killing and those who argue that failing to adequately punish a man for killing his disabled daughter devalues Tracy Latimer's life.

The judge at Latimer's second trial called the murder "compassionate homicide."

'Medical malpractice'

In Canada, people who have lost all legal appeals after conviction are allowed by law to ask the government to reopen the case by making a direct appeal to the federal justice minister.

Latimer's application for ministerial review is based on an argument that while doctors could have managed Tracy's pain with strong medication like opioids, she was denied stronger drugs because they might have killed her.

In a letter to both Justice Minister Jody Wilson-Raybould and Prime Minister Justin Trudeau, Latimer's lawyer argues his case is one of those rare instances where a free pardon is warranted. (Sean Kilpatrick/Canadian Press)

"The manifest injustice in Mr. Latimer's conviction lies in the unfair and unlawful deprivation of perfectly legal pain relief for Tracy Latimer," Gratl's letter reads.

"Tracy Latimer's life should have ended 'unintentionally' as a secondary consequence of her physicians' administration of opiates to alleviate her pain; her life should not have ended by her father's merciful and intentional administration of carbon monoxide."

Gratl argues that Latimer is a victim of "medical malpractice" and that the jury may have been "misled into an honest but mistaken belief that Mr. Latimer chose not to give Tracy painkillers stronger than Tylenol."

'One of those rare instances'

Latimer was granted day parole in February 2008 and full parole in November 2010. He has since fought in Federal Court to overturn a National Parole Board decision denying him the right to travel outside Canada.

As Latimer's application points out, if the justice minister were to determine that a miscarriage of justice had taken place, one possible remedy is a new trial.

Gratl says Latimer "is prepared to accept this remedy in anticipation that a third trial would not proceed, although he appreciates that this cannot be guaranteed at this stage."

Gratl's letter says an unconditional pardon is suited to "the rare cases in which considerations of justice, humanity and compassion override the normal administration of justice."

He concludes: "The applicant submits that his circumstances are one of those rare instances."

The Department of Justice did not reply to a request for comment.