Perjury is the criminal offense of making a false statement under oath—verbally or in writing—that the witness knows to be false and that is material to the proceeding in which the statement is made. And suborning perjury or subornation of perjury is the criminal offense of procuring the perjury of another person.

Perjury is a criminal offense under both state and federal laws and may be prosecuted as a misdemeanor or as a felony offense, depending on the state or federal jurisdiction, and whether there are any aggravating factors that increase the seriousness of the crime. Perjury laws are located in state statutes—often in the penal or criminal code—and the federal perjury law is located in the United States Code at 18 U.S.C. §1621.

In Massachusetts, perjury is considered a serious criminal offense. Under Massachusetts General Laws Chapter 268, Section 1, an individual who willfully swears falsely in a judicial proceeding or other matters where an oath is required by law is guilty of perjury. This applies to both verbal statements and written declarations. The law requires that the false statement be made with the intent to mislead and that it is material to the case or proceeding. The punishment for perjury in Massachusetts can include a state prison sentence of up to 20 years, a house of correction sentence of up to 2.5 years, and/or a fine of up to $1,000. Suborning perjury, which involves persuading or inducing another person to commit perjury, is also a criminal offense and is subject to similar penalties. At the federal level, perjury is governed by 18 U.S.C. §1621, which also criminalizes the act of making false statements under oath in federal jurisdictions, with penalties that can include fines and imprisonment.