D.C. Code § 37-201.20
Every user of an automatic measuring pump or similar device, shall, when the supply of the commodity which he is measuring for sale with such pump or similar device, is insufficient to deliver correct measure of such commodity by the usual or customary method of operating such pump or device or when, for any cause whatever, such pump or device does not, by the usual or customary method of operating same, deliver correct measure, place a sign with the words, "Out of use" in a conspicuous place on such pump or device where it may readily be seen, and shall forthwith cease to use the same until his supply of such commodity is replenished or until such pump or device is repaired, adjusted, or otherwise put in condition to deliver correct measure. All automatic measuring pumps or other similar measuring devices in use shall be subject to inspection, and approval or condemnation, whether used for measuring or not.
D.C. Code § 37-201.20