However unsavory one might consider legalized marijuana, it would be wise and correct for conservatives to support Colorado in this case, thereby opposing the claim that federal law has primacy over state law Iin areas not clearly defined in the Constitution as the purview of congress.
That is one theory, and perhaps the best argument i've heard so far in favor of legalized weed.
It is, however, not the only consideration. If marijuana establishes the legitimacy of a widespread drug culture, it pretty much spells the end of this nation, because if you let the camel's nose into the tent, there will be nothing to stop the rest of the camel from coming in too.
The Libertarian arguments for legal weed are just as valid for legal Meth.