Rule 40
Rule 40 is a by-law in the Olympic Charter stating that only approved sponsors may reference "Olympic-related terms". It was introduced by the International Olympic Committee to prevent so-called ambush marketing by companies who are not official sponsors and to sanction links between athletes and unofficial sponsors during a blackout period starting nine days before the opening of the Olympic Games and continuing until three days after the closing ceremony.
Controversy sparked in the days before the 2016 Summer Olympics as rule 40 was upheld in an effort to prevent companies from retweeting anything from the official Olympic Twitter account, or use official hashtags such as #Rio2016 and #TeamUSA. The United States Olympic Committee sent letters to companies sponsoring individual athletes but with no official sponsorship designation with a warning that they might be infringing rights by using such hashtags or other trademarks owned by USOC.
