Sentence:  The tendency in these types of situations (as far as I can see) is that because I don't think the act itself is illegal, the police will go through your vehicle systematically lokingsic for anything wrong with it, to slap a <WSD>canary</WSD> on it (that's slang for an unroadworthy sticker) or present you with some other fine. 
Meaning of the word marked with <WSD> tags:  A yellow sticker of unroadworthiness.