I've never understood the false 'honour' thing that some people exhibit: "never grass" etc. If it is against the law and being done deliberately, inform the correct authority, simples.
If it were a mate, I'd have a word first and tell 'em what I'd do if I caught 'em again but other people, no conscience about 'grassing 'em up'.
If it were a mate, I'd have a word first and tell 'em what I'd do if I caught 'em again but other people, no conscience about 'grassing 'em up'.