53 Pa. Stat. § 13376
It shall be lawful for the councils of cities of the first class, or any committee of the same or either branch thereof, to apply to any judge of the court of common pleas of the county in which said cities are situated, who may, upon affidavit of proper and sufficient cause being made, issue subpoenas in the name of the commonwealth of Pennsylvania, to any person or persons residing in said commonwealth to appear before such councils or either branch thereof, or any committee of the same, as witness to testify their knowledge concerning any matters of inquiry which may be required of them relating to the management and accounts of any of the departments of such cities, or of any other matters which may be subject to the supervision of the councils, or either branch thereof; and, also, whenever it may be deemed necessary, to produce any books and paper writings in the possession or control of such person or persons as may contain evidence pertinent to such inquiries. Any person so called as a witness may be examined under oath and shall be liable to indictment, conviction and punishment for perjury in the same manner and to the same extent as if the witness had been called and examined before any committee of the legislature of this commonwealth, or in any judicial proceeding before any of the courts thereof, in accordance with existing laws: Provided, That the person or persons outside of cities of the first class, subpoenaed as aforesaid, shall not be required to respond to the same until they have been furnished with mileage to and from said city, at the rate of ten cents per mile and a per diem allowance of two dollars for the time their presence is desired in said city.
53 P.S. § 13376