Title 14, Section 1211 of the Code of Federal Regulations.
Adopted on July 16, 1969. NASA revoked the rule in 1977. Officially removed April 26, 1991.
This regulation gave the Administrator of NASA the extra-judicial right to quarantine under armed guard anyone who became “extra-terrestrially exposed.”
‘Quarantine’ means the detention, examination and decontamination of any persons, property, animal or other form of life or matter whatever that is extra-terrestrially exposed, and includes the apprehension or seizure of such person, property, animal or other form of life or matter whatever.”
The penalty for violating quarantine was up to $5,000, a year in jail, or both.
The law was a rallying cry for UFO enthusiasts who feared jail should they make contact, but most outcry occurred after the regulation had already been removed from the books.