D.C. Code § 36-201

A union or association of employees in the District of Columbia may adopt a device in the form of a label, brand, mark, name, or other character for the purpose of designating the products of the labor of the members thereof. A drawing of such device may be filed in the Office of the Recorder of Deeds of the District of Columbia and the Recorder shall register same in a book to be provided for such purpose and be entitled to collect $1 for each registration. A certified copy of the drawing may be obtained upon the payment of $1 for each certification.