“A 2012 study that the Department of Defense commissioned after the 2009 mass shooting at Fort Hood in Texas includes an appendix titled “Prediction: Why It Won’t Work.” The appendix observes that “low-base-rate events with high consequence pose a management challenge.” In the case of “targeted violence,” for example, “there may be pre-existing behavior markers that are specifiable.” But “while such markers may be sensitive, they are of low specificity and thus carry the baggage of an unavoidable false alarm rate, which limits feasibility of prediction-intervention strategies.” In other words, even if certain “red flags” are common among mass shooters, almost none of the people who display those signs are bent on murderous violence.
Supporters of red flag laws prefer to ignore this problem. After a mass shooting in a state that has such a law, they argue, as in this case, that it would have worked if only it had been used properly. But the problem goes deeper than that. However you weigh the risk of preventable violence against the risk of taking away innocent people’s rights, this policy has inherent limitations that mean it is bound to fail”