The said joint commission and the said Pennsylvania commission shall cause to be kept a full, fair and accurate record of all its or their proceedings, properly indexed and open to the inspection of the public. Copies of all records, documents, and papers, when duly certified by said joint commission or said Pennsylvania commission, shall be received in evidence in the several courts of this Commonwealth in all cases where the original records, documents, and papers would be admitted in evidence: Provided, however, That in any judicial controversy before any court of this Commonwealth either party may have the original records, documents, or papers produced on the service of proper process for that purpose.
36 P.S. § 3428