D.C. Mun. Regs. tit. 18, r. 18-741
The American National Standards Institute, Inc., Specifications for Protective Headgear for Vehicular Users, Z90.1-1966, are adopted as the minimum standards for helmets required to be worn by operators and passengers on motorcycles or autocycles, except as set forth in § 2215.7.
In addition to the standards set forth in § 741.1, protective helmets shall be so designed so as to permit the following:
Each helmet approved by the Director shall be permanently labeled on the outside of the helmet above the base of the rear of the helmet in letters or numbers at least one-fourth inch (1/4 in.) in height with the manufacturer's trade name and number under which the helmet has been approved.
The identification label shall be permanent, weather-proof, water-resistant, and of a type which will be self-destructive when removed.
Each approved helmet shall have a reflectorized surface on both sides or have securely affixed to the helmet reflectorized material on both the left and right side of the helmet.
Reflectorization shall cover an area of at least four inches (4 in.) on each side of the helmet.
If reflectorized material (such as a one-inch by four-inch (1 in. x 4 in.) strip of reflectorized safety tape) is attached to each side of the helmet, it shall be affixed in a permanent, weather-proof manner.
An approved helmet shall be equipped with either a neck or chin strap.
D.C. Mun. Regs. tit. 18, r. 18-741