Me. Rev. Stat. tit. 29-A, § 2109

A person commits a traffic infraction if that person signals a moving vehicle, stops a vehicle or accosts an occupant of a vehicle stopped on a public way to solicit a contribution or subscription, or sell merchandise or a ticket of admission to an entertainment or public gathering. This section does not apply to an event or project conducted by a charitable nonprofit organization incorporated in or recognized by the State that has received municipal and local law enforcement authorization, including approval for the organization's traffic routing, schedule and procedures for the event or project.