The federal Armed Career Criminal Act (ACCA) acts pretty much like a three-strikes law, although it counts any violent felony or serious drug conviction as a strike, whether it resulted in a federal or state conviction. Federal law generally prohibits felons from possessing firearms, but the ACCA goes further. For people who have been convicted of three qualifying felonies, a gun conviction results a mandatory 15-year sentence in federal prison.

Since state offenses can count as qualifying felonies under the ACCA, and since these laws are always changing, there has been a great deal of litigation over precisely which state crimes count as violent felonies. To determine that, courts are to rely on the wording of the state statute rather than the details of the individual case. If the state statute covers any conduct that doesn’t qualify as a violent felony, the courts then determine whether the particular defendant’s conviction involved violence.

This can matter a lot to the defendant. An ordinary conviction for a felon in possession of a firearm typically results in a maximum 10-year sentence. The ACCA adds five years to that sentence.

What, legally, counts as violence? Is snatching a necklace violent?

In the case before the court, the defendant disputed whether one of his felony convictions should count as a violent felony for the purposes of the ACCA. He had been convicted of robbery in Florida after snatching a necklace off of someone’s throat. Is that violent? How about purse snatching or pickpocketing?

Writing for a 5-4 majority, Justice Clarence Thomas said that violence is defined by the victim’s resistance to it — and Florida’s robbery statute requires proof of the victim’s resistance.

“The force necessary to overcome a victim’s physical resistance is inherently ‘violent,'” wrote Justice Thomas.

“Robbery that must overpower a victim’s will – even a feeble or weak-willed victim – necessarily involves a physical confrontation and struggle,” he continued. “The altercation need not cause pain or injury or even be prolonged; it is the physical contest between the criminal and the victim that is itself ‘capable of causing physical pain or injury.'”

Therefore, since there was proof of resistance, the robbery conviction counts as a violent crime for the purposes of the ACCA.

In dissent, Justice Sonia Sotomayor pointed to how little force is necessary for a Florida robbery conviction. “Under Florida law, ‘robbers’ can be glorified pickpockets, shoplifters and purse snatchers,” she wrote.

A harsh ACCA sentence, she argued, is bad policy when there is any question about the violent nature of the underlying convictions. This is because people with marginal convictions are not necessarily the dangerous career criminals the ACCA aims to lock up.