It's the Flag Code, which specifies no punishment for non-compliance, nor an agency that would enforce the rule. It is also a statute that nobody fully follows, especially the hyper-patriotic. Sticking a flag on your car's antenna is grossly out of line, for instance. Heck, if you see the picture that got Barak in trouble here (http://www.snopes.com/politics/obama/anthem.asp), it isn't quite clear to me that any of the people on that stage are directing their attention towards a flag.