The case of retired Court of Appeal judge Jacques Delisle is back before the courts as justices deliberate on his request to appeal the life sentence he received for his wife's murder.

Delisle's lawyer, Jacques Larochelle, asked the Court of Appeal to either let his client go or grant him a new trial.

The former judge was sentenced to life in prison last June for the murder of his wife, Nicole Rainville, in 2009.

Larochelle said he believes there is reasonable doubt over whether Delisle, 77, committed the murder.

He said assumptions made by the crown prosecutor in court could have prejudiced his client before the jury.

He said allegations like Delisle's possible financial motives behind the crime could not be proved.

Larochelle said it was up to the trial judge, Claude Gagnon, to make sure the jury had the proper instructions as to what testimony to keep or throw out in order to render a verdict.

Crown Attorney Steve Magnan acknowledges he made a mistake when addressing the jury.

He said he told the jury they had to decide whether Rainville's death was a murder or a suicide.

Instead, Magnan said he should have asked the jury to decide beyond any reasonable doubt if Rainville had been murdered by Delisle.

Magnan said in spite of his mistakes, the jury was instructed by the judge to take into account the crown's entire expert testimony.