Marijuana prohibition is unique among American criminal laws. No other law is both enforced so widely and harshly and yet deemed unnecessary by such a substantial portion of the populace. Hundreds of thousands of Americans a year are arrested for marijuana. Doors are kicked in. Children are put into foster care. Cars, houses and bank accounts are seized without trial. Yet it's hard to find a presidential candidate or Supreme Court justice who hasn't smoked marijuana. Reform will happen.

The fact that more high school students now smoke pot than cigarettes says more about our successful tobacco policy than the consequences of medical marijuana.

The acceptance of medical marijuana has implications that extend far beyond helping those suffering from life-threatening diseases. It is one of several factors -- including demographic changes, the financial crisis, and the widely perceived failure of the war on drugs -- reopening the country's 40-year-old on-again, off-again shouting match over whether marijuana should be legalized.

What should be done about the millions of people in the United States and around the world who inject heroin and other drugs? For 30-plus years, the U.S. has pushed a "war on drugs" that is more accurately a war on drug users. This war on drugs has not delivered on its promise to keep drugs off our streets or to prevent people from using, but it has filled our prisons beyond capacity and led to far too many cases of HIV/AIDS related to sharing contaminated needles.