The ruling came in the case of a man convicted of trying to lure a 13-year-old boy, QMI Agency reported.
The defendant, Michell Rayal Levigne, who was 46 at the time, was found guilty of trying to lure a teenage Edmonton boy, "Jessy G," who actually was a police detective posing as a youth.
Levigne contended in his appeal that he didn't believe the person he was chatting with online was 13 because he typed too fast and his profile said he was 18. The Crown countered the officer repeatedly told Levigne he was 13 and in Grade 7.
The high court decided Levigne didn't make any attempt to determine the person was 18.
"The 'reasonable steps' invoked by (Levigne) were in fact neither 'reasonable' nor 'steps to ascertain the age' of the person with whom he was communicating by computer for the avowed purpose of his own sexual gratification," Justice Morris Fish wrote in a unanimous decision.
The court didn't lay out what actions would be considered reasonable.
Levigne, who had been acquitted by a lower court in 2008 before an appellate court overturned that decision and found him guilty, will now face sentencing back in a lower court.