The U.S. Supreme Court on Monday sidestepped a major constitutional decision on federal-state powers, ruling that a federal law implementing a chemical weapons treaty cannot be applied to a local dispute triggered by a Pennsylvania woman’s effort to injure her husband’s lover.

“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 for the court. No justice dissented, but several wrote concurring opinions.

Roberts wrote that Pennsylvania law was adequate to deal with the dispute at issue before the court, so the Supreme Court did not need to rule on whether the congressional enactment or the treaty infringed on state law. “Fortunately, we have no need to interpret the scope of the [chemical weapons] Convention in this case,” Roberts wrote, invoking the longstanding practice of the court not to decide a case on constitutional grounds when there are other ways to dispose of it.

In 2006, Carol Anne Bond discovered that her best friend, Mylinda Haynes, was pregnant from an affair with Bond’s husband. Bond set out to get revenge by trying to poison her friend. She acquired toxic chemicals and, at various times, placed them on the Haynes’ car, mailbox and doorknob of her home. After local police failed to help her, Haynes alerted postal authorities who placed cameras in and around her home. Bond was identified as the attacker and also was seen stealing Haynes’ mail. Bond was arrested.

Bond was charged under a statute that implements a chemical weapons treaty ratified by the United States under the Chemical Weapons Convention of 1993. The statute prohibits “knowing possession or use, for non-peaceful purposes, of a chemical that can cause death, temporary incapacitation or permanent harm to humans.” She was indicted on two counts of possessing and using a chemical weapon and two counts of theft of mail.

Bond unsuccessfully moved to dismiss the charges, arguing that Congress exceeded its authority under Article I when it enacted the implementing statute.

The district court ruled the statute was valid. On appeal, the U.S. Court of Appeals for the Third Circuit held that Bond lacked standing to challenge the statute’s constitutionality on the basis of the Tenth Amendment. Bond then made what would be the first of two trips the Supreme Court.

In 2011, the justices ruled Bond had standing “to challenge the federal statute on grounds that the measure interferes with the powers reserved to states.” On remand, the Third Circuit affirmed Bond’s conviction.

Bond’s counsel, Paul Clement of Bancroft, turned again to the Supreme Court. He argued this time that if the implementing law reaches “every malicious use of chemicals anywhere in the nation, as the government insists,” then the law violates the “bedrock principle” of federalism that there is no general police power to criminalize conduct lacking a distinct federal concern.

Clement successfully urged the justices to avoid the constitutional issue by distinguishing between “war-like” use of chemicals and non-war-like actions, such as Bond’s crime. But U.S. Solicitor General Donald Verrilli Jr. countered that the framers of the Constitution gave the federal government “exclusive control” of the treaty power “to ensure that it could knit the nation together as one and allow it to be fully sovereign in the conduct of foreign affairs.”

Contact Tony Mauro at tmauro@alm.com and Marcia Coyle at mcoyle@alm.com.