Fact: In 2011, use of marijuana by teenagers hit a 30-year peak, with one out of every 15 high school students reporting they smoke most days, and for the first time U.S. teens reported smoking more pot than cigarettes. But: teenagers don't smoke any more pot in states where medical marijuana is legal than in ones where it's not. Legalization advocates argue that the best way to reduce use by minors is to legalize and regulate pot.

Sources: New York Times, AP, Centers for Disease Control