that, however, would require most cops to even know the law they are charged with enforcing. go quiz some cop on the street about some of the only marginally less than obvious stuff about your local law (ie, is wearing a mask in public legal or does style of dress count as reasonable cause for stop and search) and you will quickly find out two things
1. they have only the most rudimentary knowledge of the law
2. anyone that points this out to them gets arrested for "obstruction"... which, given point 1, is, naturally, a false arrest.