Canada’s top court has dismissed a Mississauga man’s appeal regarding his role helping the infamous "bathtub girls" murder their mother, in a ruling that clarified a law surrounding what it means to conspire in a murder.

The Supreme Court of Canada's decision upheld the ruling by the Ontario Court of appeal and stated that the Mississauga man, who cannot be named because he was under 18 when he was arrested and convicted of conspiracy to commit murder, should indeed be found guilty of "liability to a conspiracy."

The police found an MSN chat log between the man and the two girls that provided information about death by drowning, the ruling said. The man also "suggested that the sisters should give their mother codeine pills in addition to alcohol" — the way in which the murder was ultimately committed.

Evidence was also submitted in the trial that the man took action beyond simply discussing the idea and supplied the girls with pills and met them after the murder to provide an alibi and help them avoid trouble with the police.

Broad ramifications

The court said there was so much evidence against the man that the crown could possibly have charged him with first degree murder.

An announcement on the court's website explained that the man became "a party to an offence" when he aided or abetted two Mississauga sisters' "act of agreeing" to murder their alcoholic mother.

The court's ruling is expected to have a trickle down effect, influencing the larger definition of "conspiracy to commit a crime" in future cases, the CBC's Susan Lunn reported.

Some lower courts have held a wider definition to the crime, ruling that people can be a party to a crime simply by being involved in the idea but not the action itself. Other courts have maintained a narrower definition of the criminal code, stating that someone must actually be involved in the crime to be convicted.

On top of March 1 ruling, the Supreme Court of Canada made clear that courts are to follow the narrower definition of the code. The court stated that someone can be charged with conspiracy to commit murder but that there must be some type of involvement in the commission of that crime that goes beyond simply talking about it.

Sentenced as youths

The man was originally found guilty in December 2006, after the two sisters drowned their mother in the bathtub of the family's Mississauga townhouse. He was given an 18-month sentence, 12 of which had to be spent in jail. The Ontario court of appeal upheld the charge but reduced his jail term to 8 months.

He subsequently appealed both his conviction and sentence on grounds that the trial judge made several errors.

The sisters were convicted in 2005 and sentenced in 2006 as youths. The two women, whose names also cannot be released because they were 15 and 16 at the time of the crime and subject to terms of the Youth Criminal Justice Act, were given the maximum penalty of ten years.

The verdict was delivered just a day after closing arguments finished in the case. The judge described it as “probably the strongest case I have ever seen in over 30 years of prosecuting, defending and judging criminal cases."

In 2009, a judge in Brampton, Ont. agreed to change the conditions of one of the sister’s sentences. She was to go to a halfway house in Barrie, Ont. so she could take online courses with the University of Waterloo where she was awarded a $2,000 scholarship.