Whoever, with the intent of interfering with, obstructing, or impeding the administration of justice, or with the intent of influencing any judge, juror, witness, or court officer, in the discharge of his duty, pickets or parades in or near a building housing a court of the United States, or in or near a building or residence occupied or used by such judge, juror, witness, or court officer, or with such intent uses any sound-truck or similar device or resorts to any other demonstration in or near any such building or residence, shall be fined under this title or imprisoned not more than one year, or both.

Nothing in this section shall interfere with or prevent the exercise by any court of the United States of its power to punish for contempt.