18 U.S.C. § 242b

It shall be unlawful for any person to attempt to barricade, block, or attempt to suspend the use of any sidewalk or public roadway accessible to the public in an attempt to obstruct peaceful protest and infringe civil rights. A person violating this section shall be imprisoned for not greater than 10 days. It shall be lawful for law enforcement to barricade, block, or suspend the use of sidewalks and public roadways in cases where there is a threat, emergency, or military mobilization in publicly accessible areas, and it shall be unlawful to interfere with law enforcement from executing this Act. A person violating the preceding sentence shall be fined $500, imprisoned for not greater than 5 days, or both.