Md. Code, Labor and Employment § 4–313

(a) A court may not grant injunctive relief in a labor dispute:

(1) if the plaintiff has failed to comply with each obligation imposed by law that is involved in the labor dispute; or

(2) except as provided in subsection (b) of this section, if the plaintiff has failed to make every reasonable effort to settle the labor dispute:

(i) by negotiation; or

(ii) with the help of available dispute resolution mechanisms, governmental mediation, or voluntary arbitration.

(b) If irreparable injury is threatened, a court may grant injunctive relief before another tribunal acts to settle the labor dispute.