Canada used to be really strange about bondage. In 2000 when I was working porn retail we kept our bondage stuff behind the counter. The way it was explained to me was that the bondage part was fine (getting restrained) and the sex part was fine but when you combine the bondage and the sex it becomes a "depiction of rape".

I believe that has been relaxed these days (all porn in Ontario used to need a mandatory Ontario Film Review Board "Adult Sex Film" sticker too. I always imagined some room somewhere where my fellow Ontarians had to watch every single porn that came into the province and decide if we could handle seeing it or not.

I still have some cassettes with OFRB sex film stickers on them if any posters want me to post a pic.