Md. Code, Public Utilities § 4–504

(a) This section applies only to a public service company that is an investor–owned electric company, gas company, or combination gas and electric company.

(b) A public service company may not recover through rates any costs associated with:

(1) membership, dues, sponsorships, or contributions to an industry trade association, group, or related entity exempt from taxation under § 501(c)(6) of the Internal Revenue Code; or

(2) the acquisition, use, or allocation of costs associated with a private plane that is owned or leased by the public service company or its holding company.