There's a ton of law around 'lawful orders' by the police, and how a citizen is supposed to respond to them. Ignoring everything else (please), George Zimmerman was accused of not following a 911 operator's "lawful order" to leave the scene. While I think most of America would have been happy for him to have heeded that device, it is not necessarily a 'lawful order', unless there was a reason for him not to have been there.
A lot of Americans presume "not unlawful orders" or "reasonable orders" to be presumed legal, if those orders come from a law enforcement officer, but in actuality, most lawful orders that are given are not lawful as they are not predicated on authority. If an officer tells you to leave your home, for example, that is not a lawful order unless you're under arrest, or if you're interfering with their effecting a warranted search. As such, people see orders like "Go stand over there" as being followed on television shows, and assume that the state (or its officers) have the authority to tell you where to stand. Generally speaking, they do not, usually.
The problem is in the myriad of exceptions -- we have the freedom to assemble, generally, but that assembly must be lawful. It's pretty obvious to say that we don't have the freedom to assemble on a trafficked highway, for example. Similarly, many 'free speech zones' require permits for use. That may seem unlawful, where those permitted places are common areas, but their issuance is predicated on the idea that if a 'pro' group and an 'anti' group are attempting to protest in the same space, then violence might reasonably ensue. The fix for that is to permit the space, and permit issuance is done on a first-come basis. The contra-position there is that the opposing protestors are effectively allowed to protest _anywhere but within the permitted space_, so, across the street is generally fine, and is also generally does not require a permit. A police officer at a protest may well be making a lawful order if you're in the wrong assembly area.
So yeah, it's interesting, and it's completely convoluted, and while I generally scoff at people who don't know even the basics, it's pretty near impossible to understand the intricacies of what does or doesn't comprise a lawful order depending on a myriad of circumstances. To be sure though, I think it's safe to say that most lawful orders are in fact not predicated on any actual authority, and are hence unlawful.