[Blarg]

Also many European filmmakers disregard this rule entirely. The 180 degree rule is a stylistic counterpart of the very American "principle of narrative economy," that keeps everything as clear and direct as possible. It's one of the things that can make our movies go down so smoothly -- the camera is always right where you want and expect it to be, and you never have to guess or be disoriented.

Some others either don't give a damn, or are sloppy, and some even do it for stylistic reasons. It can be surprising both how often this very good rule is ignored, as well as how a film sequence can get along fine and sometimes not even be very jarring, anyway. Once you expect the 180 degree rule to be inviolate, and learn to value it, it can suddenly leap out at you when it's disregarded.