In a study of more than 38,000 males who were arrested for crimes roughly equivalent in severity to felonies in the United States, the research team found that being added to the DNA database reduced reoffending by a stunning 43 percent. The harsher criminal sentences that are favored by self-styled “tough on crime” politicians have shown no evidence of producing a comparable level of crime reduction.
Because DNA evidence is found at many crime scenes (e.g., most rapes and other violent assaults), DNA databases raise the odds that the offender will be identified and convicted. As has been shown in many other criminal justice programs (e.g., “swift, certain, and fair” supervision programs discussed in Wonkblog here and here), raising the likelihood of being punished deters repeat offending far more than does increasing the severity of criminal penalties. Study team member Jennifer Doleac of the University of Virginia said that even uneducated offenders who don’t fully understand what DNA is nonetheless are deterred from recidivism after being added to the database because “television crime shows have a big impact on what people believe about the power of these tools.”
Denmark, of course, differs from the United States in many respects. But Doleac’s study of U.S. DNA databases also found that they produce sharp drops in criminal reoffending. Her U.S. work further notes that deterring a crime via DNA databases costs less than 10 percent of the cost of producing the same deterrent effect by building more prisons. And because DNA-related technology is getting cheaper every year while prisons remain as costly as ever, that favorable cost-effectiveness ratio is only going to rise.