Cannabis and driving

Hola!

I smoke once a month (an addiction, yes) and because THC metabolites (THC-COOH in my case) in "large" (I'm a fatty mcfatso, yes) people can stay a month in the bloodstream I have the following question: How tolerant is the police for these metabolites? (I don't condone smoking and driving, done it too much till I realized about the dangers, luckily no accidents).