Jonah — Here’s a little quibble with your scenario of what to expect were heroin a “legitimate business.” The experience with both drug and alcohol prohibition suggests that potency would decrease not increase. For instance, during alcohol prohibition, hard liquor’s proportion of alcohol consumption skyrocketed, and it came back down once alcohol was legalized (and its share has continued to ebb). Prohibition creates a substantial incentive to pack the biggest bang in the smallest package.