Legal arguments aside, it would nearly be impossbile for you to get caught as a moving jammer.
Unless, you did it everyday habitually, and enough people complained, and the FCC actually got out of their office and put a tracking truck on the route you take at that time of day.
Still would be a good idea to have one, but the down side is, it would actually just raise the frustration factor for the cellphone user. Wondering why it quit, and looking directly at the cellphone to see what happened.
Now you know they don't have their eyes on the road.
Mixed bag. In a theatre? Oh yeah!! Turn it on, guy in front looses his conversation and you turn it off. He trys to redial, you turn it back on. He finally gives up in disgust.