Q: A few months after he got his driver's license, we found a bag of marijuana in our 16-year-old son's car. He swore it wasn't his and that he didn't know whose it was and that he's never used pot, but then he failed to pass a drug test. Now he admits that he's smoked pot, but he says he only tried it once and didn't like it. He still maintains that the pot we found in the glove box of his car belonged to someone else, but he still maintains that he doesn't know who. We think he's lying to us, but we don't know what to do. Pot is legal in our state now, which only contributes to our dilemma. Can you help us out?