If I drive speeding past a cop, but didn't get a ticket, did I break the law?

I mean, if you change it to "if Bob murdered a guy in cold blood (i.e. not defense, etc.) and no one was looking, did Bob break the law?" The answer to me wouldn't be anything but yes.

Just because the offense is different or you don't agree with it doesn't change that in my eyes. It generally doesn't change it in the eyes of the law, either. Always campaign against laws you think are bullshit. If enough people do, you might be able to do something about it.