District of Columbia Code Division VIII. General Laws. § 49-404. Duty of enrolled militia;  police and fire department personnel.

The enrolled militia shall not be subject to any duty except when called into the service of the United States, or to aid the civil authorities in the execution of the laws or suppression of riots.  However, if the enrolled militia is called to aid the civil authorities, who already have activated, or will concomitantly activate, the police and fire departments, no member of these departments shall be subject to duty in the militia.  Also, if the enrolled militia is called into service of the United States, the chief of the police department and the chief of the fire department shall be entitled to have exempted from call in the militia minimum personnel considered necessary to ensure continued, reasonable police and fire services to the citizens of the District of Columbia.