My son was pulled over by a state patrol for no license plate light. The officer smelled marijuana and arrested my son (he's 17) for operating under the influence. He collected a urine sample and it is being sent to a lab to be tested. My question is how long after marijuana is smoke will it show up in urine. My son is very athletic with no body fat, assuming he is telling the truth that he hadn't smoked for a few weeks, I am wondering if the test will come back positive.