D.C. Mun. Regs. tit. 4, r. 4-805
All entities covered under the Act shall provide access to and the safe use of facilities that are segregated by gender.
In gender-specific facilities where nudity in the presence of other people is customary, entities covered by the Act shall make reasonable accommodations to allow an individual access to and the use of the facility that is consistent with that individual's gender identity or expression, regardless of whether the individual has provided identification or other documentation of their gender identity or expression.
Requiring documentation or other proof of an individual's gender is prohibited, except in situations where all persons are asked to provide documentation or other proof of their gender for a reasonable business or medical purpose.
D.C. Mun. Regs. tit. 4, r. 4-805