D.C. Code § 49-312
Any commissioned officer in the National Guard of the District of Columbia who shall have served as such in the National Guard of the District of Columbia for the continuous period of 10 years may, upon his own application, be placed by the President of the United States upon a retired list, which is hereby authorized, with the rank held by him at the time such application is made; provided, however, that an officer so retired, who at the time of making such application has remained in the same grade for the continuous period of 10 years, or whose services have been especially meritorious, may be retired with increased rank of 1 grade and shall, before being so retired, receive from the President of the United States the commission of the new grade; provided further, that whenever any officer on the active list reaches the age of 64 years he shall be retired; with or without increase of rank in the discretion of the President of the United States. Retired officers on occasions of ceremony may, and when acting under orders, as hereinafter provided, shall wear the uniform of the highest rank attained by them in the military service of the United States, the militia of the states or territories, or the National Guard of the District of Columbia. Retired officers shall be eligible to perform any military duty to the same extent as if not retired, and the Commanding General may, in his discretion, by order, require them to serve upon military boards, courts of inquiry, and courts-martial, or to perform any other special or temporary duty, and for such service they shall receive the same pay and allowances as are provided by law for like service by officers on the active list of the National Guard of the District of Columbia. All retired officers shall be amenable to court-martial for military offenses to the same extent as if upon the active list of the National Guard of the District of Columbia. The names of all officers of retired rank shall be borne upon a separate roster, kept under the supervision of the Adjutant General. The Commanding General may at any time recommend to the President of the United States and the President may retire any commissioned officer who shall have been ordered before a medical board consisting of at least 3 commissioned medical officers and upon whom such a board shall have made report showing such officer to be physically unable to properly perform the duties of his office.
D.C. Code § 49-312