D.C. Code § 47-2853.101

For the purposes of this part, the term “practice of interior design” means providing or offering to provide consultations, preliminary studies, drawings, specifications, or any related service for the design analysis, programming, space planning, or aesthetic planning of the interior of buildings, using specialized knowledge of interior construction, building systems and components, building codes, fire and safety codes, equipment, materials, and furnishings, in a manner that will protect and enhance the health, safety, and welfare of the public whether one or all of these services are performed either in person or as the directing head of an organization.