D.C. Code § 35-202
Every street railroad company or corporation owning, controlling, leasing or operating 1 or more street railroads within the District of Columbia shall on each and all of its railroads supply and operate a sufficient number of cars, clean, sanitary, in good repair, with proper and safe power, equipment, appliances and service, comfortable and convenient, and so operate the same as to give expeditious passage, not to exceed 15 miles per hour within the city limits or 20 miles per hour in the suburbs, to all persons desirous of the use of the said cars, without crowding said cars. The Public Service Commission is hereby given power to require and compel obedience to all of the provisions of this section, and to make, alter, amend and enforce all needful rules and regulations to secure said obedience; and said Commission is given power to make all such orders and regulations necessary to the exercise of the powers herein granted to it as may be reasonable and proper; and such railroad companies or corporations, their officers and employees, are hereby required to obey all the provisions of this section, and such regulations and orders as may be made by said Commission. Any such company or corporation, or its officers or employees, violating any provision of this section, or any of the said orders or regulations made by said Commission, or permitting such violation, shall be punished by a fine of not more than $1,000. And each day of failure or neglect on the part of such company or corporation, its officers or employees, to obey each and all of the provisions and requirements of this section, or the orders and regulations of the Commission made thereunder, shall be regarded as a separate offense.
D.C. Code § 35-202