From wikipedia:
While in Congress..."Barr was a strong supporter of the War on Drugs and adamantly opposed the legalization of medical marijuana. He successfully inserted an amendment in a District of Columbia funding bill that blocked the implementation of a medical marijuana initiative that had passed a referendum. He remarked that marijuana "has no place in medicine, no place in pain relief, and ... no place around our children."
From a 2006 Reason interview:
"...certainly there's a lot of room in the Libertarian Party for people who have differing views on drugs, or differing views on other issues, and that's the sign of a mature party, that it will accommodate those differences."