Prohibition doesn't work and Mencken and everyone else knew it. I suspect he would speak similarly of the failed War On Drugs of our own age.
“Five years of Prohibition have had, at least, this one benign effect: they have completely disposed of all the favorite arguments of the Prohibitionists. None of the great boons and usufructs that were to follow the passage of the Eighteenth Amendment has come to pass. There is not less drunkenness in the Republic, but more. There is not less crime, but more. There is not less insanity, but more. The cost of government is not smaller, but vastly greater. Respect for law has not increased, but diminished.”
This quote is from his editorial, "Five Years of Prohibition", American Mercury 3, December 1924, p 420-422
