Md. Code, Courts and Judicial Proceedings § 5–120

(a) This section applies to an action for injunctive relief or damages for:

(1) A violation of a collective bargaining agreement covering an employee of the State or a political subdivision of the State; or

(2) A breach by an exclusive representative of the duty of fair representation owed to an employee of the State or a political subdivision of the State.

(b) An action subject to this section shall be commenced within 6 months after the later of:

(1) The date on which the claim accrued; or

(2) The date on which the complainant knew or should reasonably have known of the breach.