Maryland Code, State Personnel and Pensions § 9-402

(b)(1) If an employee is scheduled to work on a holiday or is employed in a unit that provides a service continuously on a 7-day-a-week basis, the employee may use personal leave only after obtaining approval from the employee's appointing authority.

(2) If the request is made to observe a religious holiday, the appointing authority may deny the request only if:

(3) If the request is made for any other reason, the appointing authority may deny the request only if the denial is necessary because of a critical shortage of staff in the employee's unit.