A law passed by Congress to give domestic effect to an international chemical weapons treaty does not apply to the case of Carol Anne Bond, who used harmful chemicals to cause a minor burn on the thumb of a woman who slept with her husband. That's according to the Supreme Court's unanimous ruling in Bond v. U.S. In his majority opinion, Chief Justice John Roberts wrote that "the global need to prevent chemical warfare does not require the Federal Government to reach into the kitchen cupboard."
The law in question here is the Chemical Weapons Convention Implementation Act of 1998, which forbids anyone from “possess[ ing] or use[ing] . . . any chemical weapon,” where a chemical weapon is defined as a "toxic chemical or its precursors." It's a law passed by Congress to domestically enact the "International Convention on the Prohibition of the Development, Production, Stockpiling, and Use of Chemical Weapons and on Their Destruction," an international treaty. While the court seems to have avoided making a decision on whether the Chemical Weapons Act is itself a result of an unconstitutional congressional overstep, it did rule that the law does not apply to Bond's poisoning attempt. To make this point, Roberts began his opinion with a reference to a painting that does show the effects of actual chemical weapons use: John Singer Sargent's Gassed.