one of a number of laws passed by states in the US that are known officially as mandatory sentencing laws. The laws make it possible to give a life sentence to someone who is found guilty of a crime on three occasions even though the crime itself would otherwise receive a much shorter sentence. The laws were first introduced in the 1990s and there have been many protests against them. The term ‘three strikes’ comes from baseball, where a ↑batsman has three attempts to hit the ball before being ‘out’.
Useful english dictionary. 2012.