A man is arrested after police found drug paraphernalia in a home in Camden, New Jersey, October 22, 2006. (Photo: Tyler Hicks / The New York Times)

Global health experts agree that the war on drugs has done more harm than good, but millions of people continue to be arrested for nonviolent drug offenses each year, including 1.5 million in the US alone. Why are politicians so far behind, even as calls for legalization go mainstream?