The tal-shaya was a deadly Vulcan martial arts technique that was considered a merciful form of execution in ancient times on Vulcan. This precise technique was performed by applying pressure to the victim's neck, causing it to snap instantly.
In 2268, during his journey to the Babel Conference aboard the USS Enterprise, Ambassador Sarek of Vulcan was considered to be the logical suspect in the murder of Ambassador Gav, who had been killed by means of the tal-shaya. Sarek was later found to be innocent when the real assassin was discovered. (TOS: "Journey to Babel")