General Order No. 6

In 2270 (stardate 5275.6), Spock invokes Starfleet General Order #6 when the entire Enterprise crew except himself has been stricken with the deadly Dramian plague. According to Helmsman Sulu, the order is, "If everyone onboard has perished at the end of 24 hours, the ship will self-destruct in order to protect other beings from the disease onboard."