In that essay, I quoted Frank Zimring’s position on the impact of the war on drugs on violent crime as so: He also argues (pp.90–99), correlating hospitalizations and deaths from overdose with changes in the known street price, that overall use of cocaine appears to have remained relatively constant across the period of time in which New York City’s crime drop took place. Yet, he notes (pp.91–92) that “The peak rates of drug–involved homicide occurred in 1987 and 1988”—the same year that 70% of arrestees were found to test positive for cocaine—“and the drop in the volume of such killings is steady and steep from 1993 to 2005. … The volume of drug–involved homicides in 2005 is only 5% of the number in 1990.” Meanwhile, whereas 70% of arrestees in the late 1980s tested positive for cocaine, by 1991 (see table 2 on page 14) this number hit a low of 62%—and in 1998 it had fallen all the way to 47.1%. By 2012 (see figure 3.7 on page 45) this number fell even further to 25%.
What happened here? Why would drug use amongst arrestees fall if drug use as a whole remained constant? Zimring has an important answer: “If I’m a drug seller in a public drug market and you’re a drug seller in a public market, we’re both going to want to go to the corner where most of the customers are. But that means that we are going to have conflict about who gets the corner. And when you have conflict and you’re in the drug business, you’re generally armed and violence happens. … Policing … [helped drive] drug trade from public to private space. … [this] reduced the risk of conflict and violence associated with contests over drug turf. The preventive impact [of these policies] on lethal violence seems substantially greater than its impact on drug use. … [And] once the police had eliminated public drug markets in the late 1990s, the manpower devoted to a special narcotics unit [whose funding had increased by 137% between 1990 and 1999] dropped quite substantially [and yet the policies’ impacts on homicide rates remained].”
However, Zimring is clearly incorrect that the drug war reduced drug–involved homicides without reducing drug use as a whole—the drug war reduced drug use, too.
Quoting James Q. Wilson in the Wall Street Journal in 2011: “Another shift that has probably helped to bring down crime is the decrease in heavy cocaine use in many states. … Between 1992 and 2009, the number of admissions for cocaine or crack use fell by nearly two-thirds. In 1999, 9.8% of 12th-grade students said that they had tried cocaine; by 2010, that figure had fallen to 5.5%.
What we really need to know, though, is not how many people tried coke but how many are heavy users. Casual users who regard coke as a party drug are probably less likely to commit serious crimes than heavy users who may resort to theft and violence to feed their craving. But a study by Jonathan Caulkins at Carnegie Mellon University found that the total demand for cocaine dropped between 1988 and 2010, with a sharp decline among both light and heavy users. … Drug use among blacks has changed even more dramatically than it has among the population as a whole. As Mr. Latzer points out—and his argument is confirmed by a study by Bruce D. Johnson, Andrew Golub and Eloise Dunlap—among 13,000 people arrested in Manhattan between 1987 and 1997, a disproportionate number of whom were black, those born between 1948 and 1969 were heavily involved with crack cocaine, but those born after 1969 used very little crack and instead smoked marijuana.
The reason was simple: The younger African-Americans had known many people who used crack and other hard drugs and wound up in prisons, hospitals and morgues. The risks of using marijuana were far less serious. This shift in drug use, if the New York City experience is borne out in other locations, can help to explain the fall in black inner-city crime rates after the early 1990s.”
Thus, because “drug use among blacks has changed even more dramatically than it has among the population as a whole”, if the black:white ratio of those in prison for drug use is larger than the black:white ratio of drug users in the general population, this may be because much of the disproportionately black number of users of cocaine have already been arrested—to the benefit of the black population as a whole.
Similarly, “In a recent article in the American Sociological Review, my colleagues and I [Gary LaFree] found that a proxy measure of crack cocaine had a greater impact on big city crime than more common measures like unemployment.”
A 1994 study by Eric Baumer found that “… arrestee cocaine use has a positive and significant effect on city robbery rates, net of other predictors. The effect of arrestee cocaine use on homicide is more modest … [but] cocaine use elevates city violent crime rates beyond levels expected on the basis of known sociodemographic determinants.” And a 1997 Justice Department study found that “there was a very strong statistical correlation between changes in crack use in the criminal population and homicide rates … In five of the six study communities, … homicide rates track quite closely with cocaine use levels among the adult male arrestee population.”