WAC 308-330-472
WAC 308-330-472. Interfering with processions
(1) No person shall unreasonably interfere with a procession.
(2) No person shall operate a vehicle that is not part of a procession between the vehicles of the procession. This provision shall not apply at intersections where traffic is controlled by traffic control devices unless a police officer is present at such intersections to direct traffic so as to preserve the continuity of the procession.