EDMONTON - An Edmonton judge who used an unconstitutional section of the Criminal Code in his murder verdict is considering whether or not to grant a mistrial in the case.

Crown and defence lawyers appeared Monday before Justice Denny Thomas, who asked them to submit written arguments in the next two weeks about a possible mistrial for Travis Vader.

Prosecutor Ashley Finlayson told court the Crown is opposed to the move.

The defence applied for a mistrial shortly after Thomas convicted Vader of second-degree murder in the 2010 deaths of Lyle and Marie McCann, whose bodies have never been found.

In his reasons, the judge used a section of the Criminal Code that the Supreme Court declared unconstitutional in 1990.

Thomas said the case will resume Oct. 31, when he may be ready with a decision about a mistrial.

He also asked lawyers to come up with dates for a possible sentencing hearing.

Thomas made no mention of his widely criticized mistake in the verdict — a reference to Section 230 of the Criminal Code, which allows for a second-degree murder verdict if a killing occurred during the commission of another crime, such as robbery. Otherwise, the killing must be intentional for that verdict to be reached.

Thomas said in his verdict that Vader was a desperate drug addict who came across the McCanns in their motorhome and shot them during a robbery. But he said there was no evidence that Vader intended to kill the couple.

Law professors say the verdict isn't likely to stand and it's also possible the trial could be reopened.

"I think no matter which road you go down, it ends up in a manslaughter verdict," says Peter Sankoff, a law professor at the University of Alberta.

"It just seems to me to be the most likely option."

The McCanns, both in their late 70s, disappeared after setting out on a camping trip to British Columbia from their hometown of St. Albert, a bedroom community north of Edmonton.

Their burned-out motor home and a vehicle they had been towing were discovered west of Edmonton a few days later.

The trial heard that Vader's DNA and a fingerprint were found in their SUV and that their cellphone was used to call Vader's former girlfriend.