An accessory after the fact is a person who (1) assists someone who has committed a crime, (2) after the commission of the crime, (3) with knowledge that the person committed the crime, and (4) with the intent to help the person who committed the crime avoid arrest or punishment. The United States Code defines an accessory after the fact has someone who knows a crime has been committed and receives the offender (harbors them), or relieves, comforts, or assists the offender in order to hinder or prevent the offender’s apprehension, trial, or punishment.

An accessory after the fact is different that an accomplice to a crime, who helps with the commission of the crime. An accessory after the fact is treated as a criminal offense separate from the criminal offense of the offender being assisted, and may be prosecuted as the criminal offense of obstruction of justice.

In North Dakota, being an accessory after the fact is a criminal offense under state law. According to North Dakota Century Code (NDCC) Section 12.1-06-07, a person is considered an accessory after the fact if they harbor, conceal, or aid an individual who has committed a felony, with the intent to enable the offender to avoid arrest, trial, or punishment. The individual must know that the offender has committed a felony or has been charged with or convicted of a felony. The punishment for an accessory after the fact is typically less severe than for the principal offense but is still a serious crime. This is distinct from being an accomplice, which involves assisting in the commission of the crime itself. At the federal level, under Title 18 of the United States Code, Section 3, an accessory after the fact is someone who assists an offender in order to hinder or prevent the offender's apprehension, trial, or punishment, knowing that a crime has been committed. The federal statute also treats this as a separate offense, which can be prosecuted as obstruction of justice.