D.C. Code § 1-204.93

There shall be a Public Service Commission whose function shall be to insure that every public utility doing business within the District of Columbia is required to furnish service and facilities reasonably safe and adequate and in all respects just and reasonable. The charge made by any such public utility for any facility or services furnished, or rendered, or to be furnished or rendered, shall be reasonable, just, and nondiscriminatory. Every unjust or unreasonable or discriminating charge for such facility or service is prohibited and is hereby declared unlawful.