text: She could be out of luck depending on what test they use.  A urine test can detect the presence of THC up to a week afterward, but there are several tests which check other tissues, and it has become very popular as of late to require a hair test because evidence of drug use stays in hair for a YEAR.\n\nShe should stop smoking pot if she wants to pass a drug test.  They've gotten awfully good at catching you, otherwise.