Carol Bond (defendant), a microbiologist, learned that Myrlinda Haynes was pregnant with Carol’s husband’s child. In order to retaliate, Bond acquired an arsenic-based compound and potassium dichromate, chemicals that were capable of causing toxic harm and, potentially, death. During a period of about a year, Bond went to Haynes’s home at least 24 times and spread the chemicals on Haynes’s car, mailbox, and doorknob. Haynes was able to avoid contact with the substances, which were largely visible. Eventually, security footage caught Bond placing the chemicals on and around Haynes’s home. Bond was charged with possessing and using a chemical weapon in violation of part of the Chemical Weapons Implementation Act (the Act), 18 U.S.C. § 229, which prohibits the possession or use of any chemical that can cause death or temporary or permanent harm to another if not intended for a peaceful purpose. The Act implements the Chemical Weapons Convention (CWC), a multilateral treaty executed to completely prohibit the development and use of chemical weapons by all parties to the treaty. Bond moved to dismiss the charges, arguing that § 229 exceeded Congress’s constitutional power and interfered with the powers reserved to the states under the Tenth Amendment. The motion was denied, and Bond took a conditional guilty plea. On appeal, the United States Court of Appeals for the Third Circuit held that Bond lacked standing to raise the Tenth Amendment claim. The United States Supreme Court reversed, and on remand, the court of appeals rejected Bond’s substantive attack on her conviction. The Supreme Court granted certiorari to determine the constitutionality of applying 229 to Bond’s case.