As Buckley said 1) the War On Drugs is, according to all measures, an abject failure, and 2) there have been highly undesirable consequences to our society which have been observed since the start of the War On Drugs, which he gave a few good examples of. That's enough for me right there. Logically, there's no need in my opinion to proceed further than that in order to convince any reasonable, liberty loving, American to see the wisdom of drug legalization for adults.