Pioneer mj legalization advocate (starting in 1965) was William F. Buckley, Jr., founder of National Review magazine and a staunch conservative with a libertarian leaning. He was adamant that the war on drugs was a governmental failure that did much more harm than good.

1. The anti-marijuana campaign is a cancerous tissue of lies, undermining law enforcement, aggravating the drug problem, depriving the sick of needed help, and suckering well-intentioned conservatives and countless frightened parents"
~William F. Buckley, Jr.

2. "Narcotics police are an enormous, corrupt international bureaucracy (...) and now fund a coterie of researchers who provide them with 'scientific support' (...) fanatics who distort the legitimate research of others."
~ William F. Buckley, Jr.

3. "More people die every year as a result of the war against drugs than die from what we call, generically, overdosing."
~ William F. Buckley, Jr.

4. "The cost of the drug war is many times more painful, in all its manifestations, than would be the licensing of drugs combined with intensive education of non-users and intensive education designed to warn those who experiment with drugs."
~ William F. Buckley, Jr., "The War on Drugs is Lost," National Review July 1, 1996.

5. "Those who suffer from the abuse of drugs have themselves to blame for it. This does not mean that society is absolved from active concern for their plight. It does mean that their plight is subordinate to the plight of those citizens who do not experiment with drugs but whose life, liberty, and property are substantially affected by the illegalization of the drugs sought after by the minority."
~ William F. Buckley, Jr., "The War on Drugs is Lost," National Review July 1, 1996.