US HB7421

Amends Title 36 of the U.S. Code to require national governing bodies to mandate that amateur athletes may only participate in Olympic, Paralympic, Pan-American, and other sanctioned athletic events corresponding to their biological sex

Defines "sex" as immutable biological classification determined at conception, with "male" defined by reproductive systems producing sperm and "female" by reproductive systems producing eggs

Applies to all competition levels sanctioned by national governing bodies, including national, regional, state, and local events

Requires national governing bodies to continue sanctioning single-sex competitions that were sanctioned during the 10-year period prior to enactment, and prohibits rescinding or altering sex-based competition categories for previously sanctioned events

Preserves the ability of governing bodies to sanction mixed-sex competitions where males and females compete together