The Canadian system is generally designed to be a dictatorship with rotating dictators every few years with the party in charge, especially if it's a majority, having almost completely unfettered control over legislation. No matter whose in charge it always looks bad. It's one of the reason we need real Senate reform to create a better check and balance system.
I do know Chretien used the ability to declare a vote a matter of confidence several times to force his own party to vote his way. The tainted blood scandal being one that sticks out most in my mind. Liberal MPs were literally crying in the House of Commons while voting to approve legislation Chretien wanted passed but they disagreed with because he classified it as a confidence vote and if they voted their conscience it would have meant a general election would have to be called.
I'm also unaware of any instances of Harper physically assaulting citizens because he didn't feel like listening to his security detail and tried pushing his way through a crowd.
Overall, without any real oversight or secondary validation it's much too easy for the current PM to dismiss all opposing viewpoints and tailor make legislation only addressing their or their parties concerns. This tends to lead to some rather bad legislation (as can be see in some of the recently passed bills). Oddly enough it is the Harper government that has made motions of moving towards an elected Senate option which would help reign in the PMs power. He has already stated that if a Province elects a Senator when a seat becomes open he will adhere to their wishes (and already has in Alberta's case) and has at times made motions towards enshrining that into federal law. Of course, reforming the Senate in any meaningful way is one of the few limits on the PM authority since it would require agreement by the various Premieres.