Astronauts Must Be quarantined In Case Of Alien Hitchhikers

The United States Congress passed the Extra-terrestrial Exposure Law in 1969. The law mandates that all astronauts returning from trips into space be quarantined for a period of time to ensure that they don’t unknowingly (or knowingly) bring back any alien life-forms. 
This was passed shortly before the Apollo 11 mission. NASA wasn’t as concerned with little green men as they were with germs never before brought to Earth that could cause an outbreak.
Strangely enough, this law has been misinterpreted by some, who believed that the law made it illegal for Americans to make contact with aliens. 
The law was repealed in 1977, after several successful space missions by NASA showed that astronauts were not carrying back contaminants from space. 
Despite this, people still post angry rants on the Internet, complaining how unfair it is that they are barred from contacting aliens and demanding that the law be repealed. Somebody should break the good news to them that it has been for decades.