Is it Legal for Canadian Networks to Block American Commercials?

Didn't see the SuperBowl last Sunday. Honestly never was a sport fan or sports-oriented for that matter. Wish I was but too late in life now I guess. As for the much talked about American TV commercials. Would've been nice to see them during the game.

Though not a football fan I would have watched if we could get American commercials here. For those who don't know when an American program is on at the same time on an American and a Canadian channel the Canadian network(they're all guilty of doing this)steals the signal. Blocks the American feed so we are forced to watch the Canadian network's logo and Canadian network's commercial on the American channel. Shouldn't be allowed.

Considering people aren't getting what they're paying for by the networks blocking American ads I'd love to hear from a lawyer. Is there a case against the cable companies when it comes to this? If so, I'll be starting a petition so Canadian networks leave the American channels as is.