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 Nevada, an accessory after the fact is recognized as a separate offense from the principal crime. Under Nevada law, a person becomes an accessory after the fact by assisting an individual who has committed a crime, knowing that the individual committed the crime, and with the intention to help the individual evade arrest or punishment. This assistance can include actions such as harboring the offender, providing comfort, or any other assistance that could hinder or prevent the offender's apprehension, trial, or punishment. The distinction between an accessory after the fact and an accomplice is significant; an accomplice is someone who aids in the commission of the crime itself, whereas an accessory after the fact provides assistance after the crime has been committed. The crime of being an accessory after the fact is often prosecuted under the broader category of obstruction of justice, which is a serious offense in Nevada and can result in criminal penalties.