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 New Hampshire, perjury is considered a serious criminal offense. It is defined as knowingly making a false statement under oath, whether verbally or in writing, that is material to the proceeding at hand. This is covered under New Hampshire's state statutes, specifically in the criminal code. The severity of the charge can vary, potentially being prosecuted as either a misdemeanor or a felony, depending on the circumstances and the impact of the false statement on the proceedings. Additionally, suborning perjury, which involves persuading or inducing another person to commit perjury, is also a criminal offense in New Hampshire. The state laws work in conjunction with federal law, where perjury is governed by 18 U.S.C. §1621. Under federal law, perjury can lead to significant penalties, including fines and imprisonment, especially if the false statements have substantial effects on federal proceedings.