D.C. Code § 28-2303

An owner of a nonnegotiable written agreement for the payment of money, including a nonnegotiable bill of exchange and a promissory note, or for the delivery of personal property, an open account, debt, and demand of a liquidated character, except a claim against the United States or the salary of a public officer, may assign it in writing, and the assignee may maintain an action thereon in his own name.