The Supreme Court of Canada is reviewing the 2007 trial of Robert William Pickton, Canada’s most notorious serial killer. At the heart of the review are instructions issued to the jury deciding the case by B.C. Supreme Court Justice James Williams. The jury asked if they could still convict the Port Coquitlam man if they believed he had accomplices. Williams said they could if Pickton had killed the women or “was otherwise an active participant in the killings.” After further deliberations they returned a guilty verdict. But the pig farmer’s defense team has appealed the case, arguing that allowing the prosecution to reframe its version of the crime, from Pickton acting alone to having accomplices, gave them an advantage that made the trial—which took five years and included 129 witnesses and 1.3 million pages of documents—unfair. The prosecution wrote a letter to the Supreme Court saying that there is overwhelming evidence against Pickton, that a retrial will almost certainly result in another conviction, and that starting over would “only serve to detract from society’s perception of fairness and the proper administration of justice.” But there is a real chance that the nine judges may order a new trial—the B.C. Court of Appeal split their decision 2-1 when presented with the same case, and responses to jury questions are one of the leading causes for overturning verdicts.