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 Montana, an accessory after the fact is defined under Montana Code Annotated (MCA) 45-7-403. This statute outlines that a person becomes an accessory after the fact if they knowingly give assistance to someone who has committed a felony, with the intent to hinder or prevent the apprehension, trial, or punishment of the felon. The assistance can include providing food, shelter, transportation, or other forms of aid. Being an accessory after the fact is a separate offense from the underlying crime committed by the principal offender and is also distinct from being an accomplice, who is someone involved in the commission of the crime itself. The penalties for being an accessory after the fact in Montana can include fines and imprisonment, and the severity of the punishment may vary depending on the nature of the felony committed by the principal offender. Additionally, under federal law, specifically Title 18 U.S.C. § 3, an accessory after the fact is someone who assists an offender in order to prevent their apprehension, trial, or punishment, knowing that a crime has been committed. This is also treated as a separate offense and can be prosecuted under the federal obstruction of justice statutes.