While there is no specific law in the United States or most international jurisdictions that explicitly uses the term "Mile High Club" or forbids sexual activity on a plane, the act is effectively illegal under broader "public indecency" and "disorderly conduct" statutes. Commercial aircraft are considered public spaces. Engaging in sexual acts can lead to charges of Indecent Exposure if witnessed by others, or more seriously, Interfering with a Flight Crew, which is a federal offense in the U.S. and can carry heavy fines or even prison time. Beyond criminal law, it is a violation of every airline's "Contract of Carriage." If caught, the crew has the authority to have you met by law enforcement upon landing, and the airline can place you on a permanent "No-Fly List." While some flight attendants may simply issue a stern warning if the act is discreet and causes no disturbance, the legal and social risks far outweigh the novelty for most travelers.