03/03/2016 05:00 EST | Updated 03/04/2017 00:12 EST

Shafia appeal to be heard in Toronto court today

Lawyers for a man convicted along with his parents of the so-called honour killings of four female family members in a trial that shocked the country are making a shocking claim of their own today in a Toronto court.

Hamed Shafia's legal team will argue in the Court of Appeal for Ontario that fresh evidence shows their client was actually a year younger than originally believed at the time of his arrest in 2009.

That would have made him 17 and subject to the Youth Criminal Justice Act, meaning, for example, that there would have had to have been a hearing to determine if he should be tried as an adult.  

Criminal defence lawyer John Rosen, who is not connected to the Shafia case and wouldn't comment on it directly, says if an appeal court finds that an accused was tried in adult court when they should have been tried in youth court, there would be just one remedy.

"They've got to quash the conviction and send it back for a hearing in front of a youth court judge about whether or not he should be sent to adult court and start all over again," he said.

Bodies found in submerged car in Rideau Canal

Hamed Shafia and his parents, Mohammad Shafia and Tooba Yahya, were all convicted of first degree murder in 2012 for the deaths of the couple's three teenage daughters and Mohammad Shafia's first wife in his polygamous marriage.

The Shafia daughters, Zainab, 19, Sahar, 17, and Geeti, 13, along with Rona Amir Mohammad, 50, were found in one of the Shafia family's cars at the bottom of the Rideau Canal in Kingston, Ont., on June 30, 2009.

The family had immigrated from Afghanistan and had been living in Montreal since 2007.

Hamed Shafia's age is just one prong of the appeal that will be heard in court Thursday.

Lawyers for all three appellants, who are serving life sentences, are also arguing that an expert Crown witness who testified at the original trial on the subject of so-called honour killings unfairly prejudiced the jury.

They are targeting the testimony of Shahzrad Mojab, a University of Toronto adult education professor connected with the school's Women and Gender Studies Institute.

Her testimony described what she called a cultural practice in parts of the Middle East and South Asia of killing women and girls whose conduct is seen to "dishonour" their families.

"Her evidence invited the jury to improperly find that the appellants had a disposition to commit family homicide as a result of their cultural background and to reject their claim that they held a difference set of cultural beliefs," the Shafias' appeal documents argue.

Rosen says appealing the admissibility of expert witnesses is a well-travelled route to a new trial.

He says one of the considerations appeal court judges look at is whether the relevance of the expert testimony justifies possibly maligning the accused.

"That's where you get to the issue of, well, is this merely a character assassination or is this evidence relevant to something other than the character or propensity of the accused," he said.

In its response to the appeal, the Crown counters that Mojab's testimony was necessary for the jury to understand the phenomenon of honour killings, which, it argued, was the motive for the murders.

The Shafias will not be in court Thursday.