FWIW, the Canadian Law against Holocaust Denial was struck down in 1992. The section read [e]very one who wilfully publishes a statement, tale or news that he knows is false and causes or is likely to cause injury or mischief to a public interest is guilty of an indictable offence and liable to imprisonment.

I note that this applied only to people publishing things they knew was false, not to people who sincerely believed what they were saying.