Re: the devil is in the detail
"It is a fundamental principle of the British legal system that the police don't get to interpret the law and, thus, decide what is legal and what is illegal."
Except the Met have been doing this for years and getting away with it.
There are too many coppers who believe the law is whatever they say it is, and will attempt to take you down for disputing that. This kind of corrupt behaviour needs weeding out - firmly.