D.C. Code § 22-3401
No person engaged in the business of collecting or aiding in the collection of private debts or obligations, or engaged in furnishing private police, investigation, or other private detective services, shall use as part of the name of such business, or employ in any communication, correspondence, notice, advertisement, circular, or other writing or publication, the words "District of Columbia", "District", the initials "D.C.", or any emblem or insignia utilizing any of the said terms as part of its design, in such manner as reasonably to convey the impression or belief that such business is a department, agency, bureau, or instrumentality of the municipal government of the District of Columbia or in any manner represents the District of Columbia. As used in this section and § 22-3402, the word "person" means and includes individuals, associations, partnerships, and corporations.
D.C. Code § 22-3401