Critics slammed both men for their remarks. But Obama and Holder were right to address the issue, and they are right on its substance.
Florida was the first to adopt a stand-your-ground statute, in 2005; about half the states have followed. Instead of requiring potential victims of crime to retreat if they have a safe escape route, these laws allow people to use deadly force without attempting to avoid a potentially lethal confrontation. They also often contain other generous protections for killers claiming self-defense.
George Zimmerman, who shot Trayvon Martin, didn't invoke Florida's stand-your-ground statute. But the law could have contributed to the police decision not to charge him for more than a month after he killed Martin. At trial, the judge informed the Zimmerman jury explicitly of the stand-your-ground law, and the statute came up in closing arguments.
There is a reason that the duty to retreat is a concept respected by centuries of legal application. Setting a laxer standard encourages tragic mistakes, poor judgment and perhaps even vigilantism. A recent study from two Texas A&M University researchers found that "lowering the expected cost of lethal force causes there to be more of it." Stand-your-ground states saw more homicides than their peers about 600 more a year over the period they studied. One possible explanation is that stand-your-ground laws encourage people to escalate conflicts rather than withdraw.
Advocates of stand-your-ground legislation point out that rates of violent crime have diminished in states such as Florida. But they've diminished everywhere. In fact, the Texas A&M study's statistical analysis concluded, somewhat surprisingly, that "the prospect of facing additional self-defense does not deter crime."
Researchers will continue to study the matter. But even before more data come in, the president's position has the virtue of making common sense.