About 3 million people — less than 1 percent of America’s population — consume 80 percent of illegal hard drugs. Drug-trafficking organizations can be most efficiently injured by changing the behavior of the 20 percent of heavy users, and we are learning how to do so. Reducing consumption by the 80 percent of casual users will not substantially reduce the northward flow of drugs or the southward flow of money.

In “Drugs and Drug Policy: What Everyone Needs to Know,” policy analysts Mark Kleiman, Jonathan Caulkins and Angela Hawken argue that imprisoning low-ranking street-corner dealers is pointless: A $200 transaction can cost society $100,000 for a three-year sentence. And imprisoning large numbers of dealers produces an army of people who, emerging from prison with blighted employment prospects, can only deal drugs. Which is why, although a few years ago Washington, D.C., dealers earned an average of $30 an hour, today they earn less than the federal minimum wage ($7.25).