D.C. Code § 5-333.04: Policy on investigations and inquiries involving First Amendment activities.

The MPD shall conduct all investigations and preliminary inquiries involving First Amendment activities for a legitimate law enforcement objective and, in so doing, shall safeguard the constitutional rights and liberties of all persons. MPD members may not investigate, prosecute, disrupt, interfere with, harass, or discriminate against any person engaged in First Amendment activity for the purpose of punishing, retaliating, preventing, or hindering the person from exercising his or her First Amendment rights.