Probably brought in because of the amount of officers nearly killed, or indeed killed, by traffic whilst arresting or interrogating someone at the side of the road. Like this:
The primary problem here lies not with the law itself, which is well intentioned (if someone draconianly implemented) but the lack of publicity surrounding the law, which may or may not be deliberate.
Hopefully this thread and the Snopes article, as well as the email/facebook post going around which is probably where this is from will help to educate people and help people avoid unnecessary fines.
