Misprision of felony

United States
Misprision of felony is a federal crimial offense in the United States. 18 U.S.C. §4:

"Whoever, having knowledge of the actual commission of a felony cognizable by a court of the United States, conceals and does not as soon as possible make known the same to some judge or other person in civil or military authority under the United States, shall be fined under this title or imprisoned not more than three years, or both."

The offense requires active concealment of a known felony rather than merely failing to report it.