The U.S. Supreme Court, sidestepping a major constitutional test of Congress’ treaty powers, ruled unanimously last week that a vengeful act by a woman whose husband impregnated her best friend did not violate a federal law implementing a chemical-weapons treaty.

“In sum, the global need to prevent chemical warfare does not require the federal government to reach into the kitchen cupboard, or to treat a local assault with a chemical irritant as the deployment of a chemical weapon,” Chief Justice John Roberts Jr. wrote in reversing the conviction of Carol Anne Bond. “There is no reason to suppose that Congress—in implementing the Convention on Chemical Weapons—thought otherwise.”