i get busted all the time in Brighton (uk)... most of the time they will ask me to turn out my pockets and they can go through them. but in a little gap in the law:

if you hide a wee stash in/under your hat... they need to take you to the station and formulate a warrant... 99% of the time they wont even bother. because for some reason the contents of a hat is private.

the worst i got was a 100 pound fine and they took my tweed away... proper class