This is Richard Posner:
The new (that is, the ostensibly new) strategy gives continued primacy to the “war on drugs,” which best describes the criminal-law and (abroad) paramilitary campaigns against the drug trade. No one thinks these campaigns can eradicate illegal drugs. The realistic-seeming objective is, by increasing expected punishment cost and by taking out of circulation (through imprisonment) those not deterred by the cost, the war on drugs raises the prices of illegal drugs. Yet those prices remain very low. The reason appears to be the very high elasticity of supply of drug dealers. It’s like Karl Marx’s “reserve army of the unemployed”; if there is no dearth of persons willing to be drug dealers at modest wages, the principal effect of law enforcement may be to increase labor turnover, at enormous cost in police and prosecutorial resources and above all in incarceration: half the federal prison population in the United States consists of drug offenders. Some 1.7 million persons who are in prison or jail (state or federal) or on probation or parole (or its federal equivalent, supervised release) are in those situations of confinement or restriction because of drug offenses. No doubt the mere fact that drugs are illegal deters some consumers — but how many relative to the large number of persons who have no interest in consuming mind-altering drugs, legal or illegal?