The Supreme Court of Canada has ruled that posting a hyperlink to defamatory material does not constitute publishing the defamation:
In its unanimous decision to dismiss the [Crookes vs Newton] case, the court said a hyperlink, by itself, should never be considered “publication” of the content to which it refers. But that doesn’t mean internet users shouldn’t be careful about how they present links. The court says that if someone presents content from the hyperlinked material in a way that repeats the defamatory content, they can be considered publishers and are therefore at risk of being sued for defamation.
The court agreed with the arguments that applying the definition of publisher to someone who hyperlinks could have a chilling effect on internet use.
“The internet cannot, in short, provide access to information without hyperlinks. Limiting their usefulness by subjecting them to the traditional publication rule would have the effect of seriously restricting the flow of information and, as a result, freedom of expression,” Madam Justice Rosalie Abella wrote.