Remember to keep smiling. When you loose your sense of humour (or your temper), they gain power and feel like their winning. I usually ignore stupid laws like that (what are they going to do, arrest me?) Plus, if you shoot like you mean it (act like a real photographer), they usually leave me alone. If I see them first, I'll go introduce myself, let them see my equip, and even ask if they would like to come watch me work.
I'm just waiting for the day when I'm shooting a wedding outdoors and some *idiot* tries their "Patriot Act" crap. I'll let the bride kick their ass for me...
Check with the law before you shoot. Just like rules, laws can be bent or broken, as long as you know them first. Hell, I have the FAA complaint 800 number in my cell phone. Therefore, if some TSA lackie decides to harass me when I fly, I'll ask for the supervisor, and then dial the FAA. Plus, I keep a copy of the 49CFR with me.
I've seen more 35mm photographers get harrassed than MF or LF people. (Try Indianapolis International Airport) I get a lot of "nice cameras" and "heading to a job, eh" from the TSA people when they see my Hassy. I was surprised. Of course, since the TSA took over, airport checkpoints have been very, very much improved in quality. No more minimum wage *idiots* who are clueless and abuse their (limited) power. The TSA folks are actually very professional, knowledgeable, and usually nice.
When I'm out and somebody is starting some sh*t with me about shooting, I usually whip out my phone and threaten to call the cops first. "Hold on one moment here while I call the local constabulary (the other person is still taking to me...) and I'll see what they have on the books for such a law" Most times, they give up and walk away, I've only had one incident where they were stubborn and stuck around. When the cops arrived, they basically told the guy he was an idiot, looked at my gear, shrugged, and walked off. If the cop told me to leave, I would, but if not, I'd smile, smile, smile, and work away. (Or, I'll take a picture of the guy who was harrasing me and threaten to use it for a billboard supporting abortion)
Yup, I'm one of those conspiracy theorizing, stubborn, "hate authority", Dead Kennedy-like people. Come'on, I'm in the computer industry. Since when were we known for being nice people? He He