This is a superb look at the history and politics of cannabis laws in the U.S. Judge Gerber does a truly excellent job explaining that today's problems stem from illogical steps taken in the 1930s. He's got a real flair for telling stories, so it's a good read.
IT IS NOT A CALL TO SELL MARIJUANA AT THE GROCERY STORE! The book explains that keeping cannabis prohibited costs us all dearly. The money, time, law enforcement resources, judicial expenses, loss of civil rights, and prohibition-induced disrespect for the law is too much to pay just to claim that we're keeping 2/3 of Americans from trying marijuana. It's a reasoned and compelling argument for first legalizing medical cannabis (as 70% of Americans are willing to do!) and then considering the removal of criminal penalties for personal possession. If those steps do not create troubles, we can all evaluate if legalization seems worth it. What could be more reasonable?