I am a huge opposer of legalization, because I've seen what pot has done to people I care about. I would point out that solution to the negatives of prohibition is not legalization, but decriminalization. The issue with legalization is that it removes the stigma with trying it, which means we get more users than otherwise.

We can maintain the very correct statements that drugs are bad and that all possible care should be made to remove it's availability and discourage it's use, but treat it as a social problem, not a crime. Let's continue to shut down drug dealers, who grow, import, and spread the crud around, but no longer penalize users. Offer them treatment, help them find better means, rather than throwing them in jail.