66 Pa.C.S. § 334

(a) Presiding officers to decide.--The same presiding officer shall to the fullest extent possible preside at all the reception of evidence in a particular case to which he has been assigned. The same presiding officer who presides at the reception of evidence shall make the recommended decision or initial decision except where such presiding officer becomes unavailable to the commission.

(b) Outside consultation prohibited.--Save to the extent required for the disposition of ex parte matters not prohibited by this part, no presiding officer shall consult any person or party on any fact in issue unless upon notice and opportunity for all parties to participate; nor shall any presiding officer be responsible to or subject to the supervision or direction of any officer, employee or agent engaged in the performance of investigative or prosecuting functions for the commission. No employee, appointee, commissioner or official engaged in the service of, or in any manner connected with the commission shall engage in ex parte communications save to the extent permitted by this part. No officer, employee or agent engaged in the performance of investigative or prosecuting functions for the commission in any case shall, in that or a factually related case, participate or advise in the decision, recommended decision or commission review, except as witness or counsel in public proceedings.

(c) Ex parte communications.--Ex parte communications prohibited in this section shall mean any off-the-record communications to or by any member of the commission, administrative law judge, or employee of the commission,

regarding the merits or any fact in issue of any matter pending before the commission in any contested on-the-record proceeding. Contested on-the-record proceeding means a proceeding required by a statute, constitution, published commission rule or regulation or order in a particular case, to be decided on the basis of the record of a commission hearing, and in which a protest or a petition or notice to intervene in opposition to requested commission action has been filed. This subsection does not prohibit off-the-record communications to or by any employee of the commission prior to the actual beginning of hearings in a contested on-the-record proceeding when such communications are solely for the purpose of seeking clarification of or corrections in evidentiary materials intended for use in the subsequent hearings.