Maryland State Personnel and Pensions Section 3-402
§ 3-402.
  (a)   A petition for the election of an exclusive representative of a bargaining unit may be filed with the Board by:
    (1)   an employee organization seeking certification as exclusive representative; or
    (2)   an employee, a group of employees, or an employee organization seeking a new election to determine an exclusive representative.
  (b)   A petition shall:
    (1)   contain the information the Board requires; and
    (2)   be accompanied by a showing of interest supported by 30% of the employees in the appropriate unit indicating their desire to be exclusively represented by the petitioner for the purpose of collective bargaining.