It is a moment in America that is rife with contradictions:

-People are looking more kindly on marijuana even as science reveals more about the drug’s potential dangers, particularly for young people.

-States are giving the green light to the drug in direct defiance of a federal prohibition on its use.

-Exploration of the potential medical benefit is limited by high federal hurdles to research.

Washington policymakers seem reluctant to deal with any of it.

Richard Bonnie, a University of Virginia law professor who worked for a national commission that recommended decriminalizing marijuana in 1972, sees the public taking a big leap from prohibition to a more laissez-faire approach without full deliberation.