Most people don't realize that under the conservative 'banner' there is a wide variety opinion on drug policy. The most well-known view is the 'law-and-order' lock'em up and throw away the key view. By contrast, The Drug Policy Alliance has this as part of their mission statement:

"The Drug Policy Alliance envisions a just society in which the use and regulation of drugs are grounded in science, compassion, health and human rights, in which people are no longer punished for what they put into their own bodies but only for crimes committed against others, and in which the fears, prejudices and punitive prohibitions of today are no more."
Makes sense. I recall reading stories of individuals locked up for some unthinkable 20-25 years on a count of marijuana possession. That's insane. Meanwhile, we have creeps like the guy who attacked and killed Dru Sjodin, let out of overcrowded jails despite previous rape convictions.
Ethan Nadelmann of the DPA wrote a cover story for National Review in July of 2004, caled "And end to Marijuana Prohibition."
The DPA has a surprising variety of supporters on the right, including one of my favs -WFB:

"85 million Americans have experimented with illegal drugs. Since the object of criminal law is to detect and punish the wrongdoer, should we reason that 85 million of us should have spent time in jail?" - William F. Buckley Jr. (Well put)

"...I wouldn't be surprised if in 10 years or so you saw the conservative coalition come out for an end to drug prohibition." -Grover Norquist, President, Americans for Tax Reform.

"Can any policy, however high-minded, be moral if it leads to widespread corruption, imprisons so many, has so racist an effect, destroys our inner cities, wreaks havoc on misguided and vulnerable individuals, and brings death to foreign countries?" -Milton Friedman

"...if your doctor prescribes marijuana, then I think that people should smoke it if they need it for medical care." - Gov. Arnold Schwarzenegger.

"...We need at least to consider and examine forms of controlled legalization of drugs." - George Shultz.

"Take it from a businessman: The War on Drugs is just money down the drain." -Gov. Gary E. Johnson