There is a fundamental difference in the way defamation is treated in Canada(and other Common law countries like the UK and Australia) and the US. This is a simplification, but basically in the US you generally need to prove that the statement was knowingly false (in addition to other defamation requirements like proving damages). This is nearly impossible to do in most situations. In Common law the person who said the statement needs to prove they had a reasonable justification for thinking the statement true. This reverses who the onus of proof is on and makes winning defamation cases in Canada actually plausible.