D.C. Code § 47-2910
The proprietor or proprietors, keeper or keepers, of any licensed restaurant, eating house, barroom, sample room, ice cream saloon, or soda fountain room shall sell at and for the usual or common prices charged by him, her, or them, as contained in said printed cards or papers, any article or thing kept for sale by him, her, or them to any well-behaved and respectable person or persons who may desire the same, or any part or parts thereof, and serve the same to such person or persons in the same room or rooms in which any other well-behaved person or persons may be served or allowed to eat or drink in said place or establishment; provided, that persons of different sexes shall not be accommodated in the same room or rooms unless they accompany each other, or call for any articles or things together, or unless said room or rooms are ordinarily used indiscriminately by persons of both sexes.
D.C. Code § 47-2910