D.C. Code § 31-4805
Any individual designated with the consent of the insurer, evidenced by the signature of its president or secretary, or designated upon a form furnished by and filed with the insurer, as beneficiary of such a policy shall be entitled to the proceeds of such policy after the death of the insured in priority to all other claimants, and may sue in his own name for such proceeds if payment is refused by the insurer; provided, that upon the expiration of 15 days after the death of the insured, unless proof of claim in the manner and form required by the policy, accompanied by the policy for surrender, has theretofore been made by or on behalf of such designated beneficiary, the insurer may pay to any other claimant permitted by the policy. A person specified as one to whom the insured desires payment made, but not formally designated as beneficiary, shall be deemed a beneficiary for the purposes of this section, provided such designation be made in writing and filed with the company during the lifetime of the insured.
D.C. Code § 31-4805