One thing i learned in 3 years of law school, never believe a cop. At least some of times they tell you something, it is completely BS, including when they "tell you what the law says." It just makes me want to scream "WHERE'S THE STATUTORY AUTHORITY JACKASS" I agree that there are lots good cops out there, but the others, when they "tell you what the law says," they are taking a SWAG (Systematic Wild Ass Guess) at best, or worse, they're just making it up as they go along.
Example: TVA police pulled into our local party slough on the 4th of July weekend. He was screaming that he'd bust up the party take everybody to jail because it is a dry county. I didn't want to backtalk the guy, but i had to remind him of the AL statute that allows each person over 21 years of age to possess up to 1 case of beer or one 1/5 of liquor in a dry county. I completely agreed with the guy at first b/c his reason for pulling up was that all the stupid rednecks were throwing their beer cans in the river. I'm glad he made his point, so maybe people wont trash my river anymore, but his threats, which had no basis under the laws of Alabama, really hit a nerve. He didnt have to outright LIE about the law; threatening to write everyone there a ticket for littering would have accomplished the same purpose. Instead he chose to misrepresent the law, and i'm guessing his motivation was at least partl to make himself feel that he was more endowed.