Missouri Attorney General Catherine Hanaway led a coalition of 12 states in filing a motion to intervene in federal court litigation defending Executive Order 14399, 'Ensuring Citizenship Verification and Integrity in Federal Elections,' issued by President Trump on March 31, 2026. The executive order directs federal agencies to compile a State Citizenship List for voter-registration verification and instructs the U.S. Postal Service to develop security rules for mail-in and absentee ballots. The coalition filed the motion in the U.S. District Court for the District of Columbia and the U.S. District Court for the District of Massachusetts.