The Supreme Court on Wednesday unanimously bolstered the federal law that bars those convicted of domestic violence from possessing a firearm.

The court gave a wide interpretation of the law’s requirement of “physical force.” The federal government said that was important because in some states, misdemeanor domestic-violence laws are not specific about the force required.

The case was brought by James Alvin Castleman, who was charged with selling firearms on the black market. He was charged with violating the federal firearms law because he had pleaded guilty in Tennessee to misdemeanor domestic violence, meaning he had “intentionally or knowingly caused bodily injury” to the mother of his child.

Because the federal law requires the “use or attempted use of physical force” and Tennessee’s misdemeanor domestic-violence law does not, a district judge agreed with Castleman that the federal charges should be dismissed. The judge said the federal law requires “violent contact with the victim.”

An appeals court agreed that violent physical force was necessary to prosecute under the federal law.

But the court, in an opinion written by Justice Sonia Sotomayor, said that was too literal a definition.

“Minor uses of force may not constitute ‘violence’ in the generic sense,” Sotomayor wrote. But even squeezing someone’s arm to the point of causing bruises “is easy to describe as ‘domestic violence,’ when the accumulation of such acts over time can subject one intimate partner to the other’s control.”

Further evidence of Congress’s intent, Sotomayor wrote, is that Castleman’s reading of the federal law would have made it ineffective at the time it was enacted. That is because 10 states did not have the physical force requirement in their domestic-violence laws.

All of the justices agreed with the outcome of the case. But Justice Antonin Scalia said that when his colleagues define domestic violence too broadly, they “impoverish the language.”

“When everything is domestic violence, nothing is,” Scalia wrote. “Congress will have to come up with a new word (I cannot imagine what it would be) to denote actual domestic violence.”

The case is U.S. v. Castleman.