OTTAWA - Twenty lives could become but a footnote this week in the history of one of Canada's most notorious serial killers.

The Supreme Court of Canada is to rule Friday on whether Robert William Pickton deserves a new trial for the murder of six women.

Pickton was convicted of second-degree murder in their deaths in December 2007.

The issue under appeal centres on whether Pickton's right to a fair trial was violated by the way the trial judge answered a question asked by the jury during the sixth day of deliberations.

But the top court's ruling has wider implications.

If the Supreme Court decides Pickton's rights in the original trial were violated and orders a new trial, it opens the door for the Crown to try him again -- not for those six deaths alone, but for 20 others as well.

And if the high court upholds his conviction, a trial on the other 20 charges likely will never happen.

All of the charges followed an exhaustive search of Pickton's farm where evidence surfaced in 2002 that finally shed light on the whereabouts of dozens of women who had gone missing from some of Vancouver's grittiest streets over more than a decade.

The first murder charges were laid just weeks after the search began, but by 2005, Pickton was facing 27 counts of first-degree murder.

One charge was eventually dropped and the judge split the others into two groups -- six to be tried at the first trial, and 20 others during a potential second trial.

At the time, the judge said, proceeding with all 26 counts would be an unreasonable burden on a jury. He also said the possibility the trial would get to a verdict without a mistrial was low.

"I am satisfied that the interests of justice require severance of counts from the present indictment," wrote Justice James Williams.

The six murder cases that went to trial first were those of Mona Wilson, Georgina Papin, Marnie Frey, Brenda Wolfe, Sereena Abostway and Andrea Joesbury.

The cases were declared by the judge to include evidence that was materially different from the other 20 counts.

But the British Columbia Court of Appeal later disagreed with the judge's decision to split the trials.

After Pickton had been convicted on second-degree murder in the six cases, he appealed and that's the case that will be decided Friday at the Supreme Court.

But the Crown also protested, arguing the decision to split the counts was wrong and that Pickton should be retried for all 26 cases.

The B.C. Court of Appeal unanimously ruled in favour of the Crown, giving the green light for prosecutors to go ahead with a new trial on all the charges.

Except they added a big "but."

"I am persuaded that the Crown's position on this issue is sound," wrote Chief Justice Lance Finch.

"If Mr. Pickton remains convicted of second-degree murder on those six counts after all appeals are concluded, there would be no useful purpose in a retrial on those same offences as charges of first-degree murder," Finch said.

At the time, the Crown agreed.

"The Crown's position has been and remains that if Mr. Pickton exhausts all of his available appeals on the six convictions and remains subject to the sentence of life in prison with no parole eligibility, the Crown will not proceed on the remaining 20 counts," spokesman Neil MacKenzie said last year.

"We understand that it's a decision that some family members are disappointed with. However, the branch has to keep in mind that any additional convictions beyond the six that he's received will not result in any further penalty or punishment being imposed."

The Crown declined to comment Wednesday on whether that remains its position.

But the B.C. Court of Appeal ruling led to what some have called the Pickton paradox.

Families of the 20 women are actually rooting for him to win his Supreme Court appeal.

"This has lingered on so long, the families are so frustrated with the way it's been handled," said Lilliane Beaudoin, the sister of Diane Rock, one of the other women Pickton is charged with killing.

"Let's get on with it, let's hear this decision and just pray it's in our favour that they will go back to trial on the 26 (cases)."

The other 19 women are: Cara Ellis, Andrea Borhaven, Kerry Koski, Wendy Crawford, Debra Lynne Jones, Tiffany Drew, Sarah de Vries, Cynthia Feliks, Angela Jardine, Diana Melnick, Jacqueline McDonell, Heather Bottomley, Jennifer Furminger, Helen Hallmark, Patricia Johnson, Heather Chinnock, Tanya Holyk, Sherry Irving and Inga Hall.

Pickton, who turns 61 in October, is currently serving a life sentence with no possibility of parole for 25 years.