Predicting 'Future Dangerousness' Is Flawed; Could a Gene Test Do Worse?
The use of genetic tests to predict a convict's "future dangerousness" is controversial, in part because the genes in question -- such as one that produces a change in a brain chemical called MAO-A and has been linked to violent behavior -- remain poorly understood.
But under current court rules, virtually any kind of evidence of future dangerousness is considered admissible for sentencing purposes, even if its scientific validity is questionable.
Indeed, the nongenetic predictors in use today are notoriously inaccurate. The test that is widely considered to be most accurate, known as the Violence Risk Appraisal Guide, scores individuals in a dozen psychological categories based on such information as age, marital status and past criminal record. It is often introduced during decisions about whether to impose the death penalty.
But this test is wrong almost as often as it is right. About 55 percent of those deemed to be at highest risk go on to commit crimes later. That means that 45 percent who might be sentenced to death for their high score would not have committed another violent crime.