Here's the long-awaited ruling. It concludes, in short, that a federal statute implementing a treaty prohibition against chemical weapons does not reach the conduct of petitioner Carol Anne Bond.
The Chief Justice authored the opinion for the court, in which Justices Kennedy, Sotomayor, Ginsburg, Breyer and Kagan joined. Justices Scalia, Thomas and Alito each wrote separately, and each concurred in the judgment. The court's opinion begins:
The horrors of chemical warfare were vividly captured by John Singer Sargent in his 1919 painting Gassed. The nearly life-sized work depicts two lines of soldiers, blinded by mustard gas, clinging single file to orderlies guiding them to an improvised aid station. There they would receive little treatment and no relief; many suffered for weeks only to have the gas claim their lives. The soldiers were shown staggering through piles of comrades too seriously burned to even join the procession.
The painting reflects the devastation that Sargent witnessed in the aftermath of the Second Battle of Arras during World War I. That battle and others like it led to an overwhelming consensus in the international community that toxic chemicals should never again be used as weapons against human beings. Today that objective is reflected in the international Convention on Chemical Weapons, which has been ratified or acceded to by 190 countries. The United States, pursuant to the Federal Government’s constitutionally enumerated power to make treaties, ratified the treaty in 1997. To fulfill the United States’ obligations under the Convention, Congress en- acted the Chemical Weapons Convention Implementation Act of 1998. The Act makes it a federal crime for a person to use or possess any chemical weapon, and it punishes violators with severe penalties. It is a statute that, like the Convention it implements, deals with crimes of deadly seriousness.
The question presented by this case is whether the Implementation Act also reaches a purely local crime: an amateur attempt by a jilted wife to injure her husband’s lover, which ended up causing only a minor thumb burn readily treated by rinsing with water. Because our constitutional structure leaves local criminal activity primarily to the States, we have generally declined to read federal law as intruding on that responsibility, unless Congress has clearly indicated that the law should have such reach.The Chemical Weapons Convention Implementation Act contains no such clear indication, and we accordingly conclude that it does not cover the unremarkable local offense at issue here.