Some state legislatures—and the United States Congress—have enacted so-called three-strikes laws (or three strikes, you’re out laws) to help law enforcement deal with violent repeat offenders—sometimes called persistent offenders, or prior and persistent offenders. The federal three-strikes law is a statute—also known as the Violent Crime Control Act—located in the United States Code at 18 U.S.C. §3559(c).

Under the federal three-strikes law, a person who is convicted in federal court of a serious violent felony and who has previously been convicted (in state or federal court) of (1) two or more serious violent felonies, or (2) one or more serious violent felonies and one or more serious drug offenses—will receive a mandatory sentence of life imprisonment.

Under the federal three-strikes law, serious violent felonies generally include federal or state offenses of (1) murder; (2) manslaughter (other than involuntary manslaughter); (3) assault with intent to commit murder; (4) assault with intent to commit rape; (5) sexual abuse and aggravated sexual abuse; (6) abusive sexual contact; (7) kidnapping; (8) aircraft piracy; (9) robbery; (10) carjacking; (11) extortion; (12) arson; (13) illegal firearms use; (14) illegal firearms possession; (15) attempt, conspiracy, or solicitation to commit any of these criminal offenses; and (16) any other offense punishable by a maximum term of imprisonment of 10 years or more that has as an element the use, attempted use, or threatened use of physical force against another person, or that involves a substantial risk that physical force against another person may be used in the course of committing the offense.

Three-strikes laws enacted by state legislatures vary from state to state—including what constitutes a strike offense—and are generally located in a state’s statutes—often in the penal or criminal code.

In Massachusetts, the three-strikes law, also known as 'Melissa's Law,' was enacted in 2012 to address repeat violent offenders. This law enhances the penalties for those who have been convicted of two prior violent crimes by imposing a mandatory maximum prison sentence without the possibility of parole for the third offense. The law defines violent crimes to include a range of offenses such as murder, rape, armed robbery, and other serious offenses that pose a significant threat to public safety. The federal three-strikes law, found at 18 U.S.C. §3559(c), mandates a life sentence for a person convicted in federal court of a serious violent felony if they have two or more prior convictions for serious violent felonies or serious drug offenses. The federal definition of serious violent felonies includes crimes like murder, sexual abuse, kidnapping, and others that involve the use or threat of physical force. It's important to note that the application of three-strikes laws can be complex, and the specific circumstances of a case will determine how these laws are applied. Individuals facing charges that could invoke the three-strikes law should consult with an attorney for guidance specific to their case.