Maryland § 4-304

§ 4-304.

    (a)    In this section, “promise” means any undertaking, whether express or implied or oral or written.

    (b)    A promise made between an employee or prospective employee and an employer, prospective employer, or any other individual, association, company, corporation, or firm is against the policy of the State if the promise requires either party:

        (1)    to join or remain a member of an employer or labor organization;

        (2)    not to join or not to remain a member of an employer or labor organization; or

        (3)    to withdraw from an employment relation if the party joins or remains a member of an employer or labor organization.

    (c)    A court may not grant, on the basis of a promise described in this section, any relief against:

        (1)    a party to the promise; or

        (2)    another person who, without the act or threat of fraud or violence, advises, induces, or urges a party to disregard the promise.