Pennsylvania microbiologist Carol Bond was thrilled to learn that her best friend was pregnant — until she found out her husband was the father. Her revenge? Spreading highly toxic chemicals on her friend’s door and mailbox handles. She was arrested, then charged under the same Chemical Weapons Convention the U.S. government levied against Syria. The U.S. Supreme Court must now ask: can Congress use the Chemical Weapons Convention to punish domestic criminal conduct? States’ rights may hang in the balance.