66 Pa. C.S. § 502
Whenever the commission shall be of opinion that any person or corporation, including a municipal corporation, is violating, or is about to violate, any provisions of this part; or has done, or is about to do, any act, matter, or thing herein prohibited or declared to be unlawful; or has failed, omitted, neglected, or refused, or is about to fail, omit, neglect, or refuse, to perform any duty enjoined upon it by this part, or has failed, omitted, neglected or refused, or is about to fail, omit, neglect, or refuse to obey any lawful requirement, regulation or order made by the commission; or any final judgment, order, or decree made by any court, then and in every such case the commission may institute injunction, mandamus or other appropriate legal proceedings, to restrain such violations of the provisions of this part, or of the regulations, or orders of the commission, and to enforce obedience thereto.
66 Pa.C.S. § 502