Procedure in hearings before commission; rules of evidence. (1) All hearings and investigations before the commission are governed by ORS 242.702 to 242.824 and by the rules and practice of procedure adopted by the commission; and in the conduct thereof, the commission is not bound by the rules of evidence

(2) No informality in any hearing or investigation, or in the manner of taking testimony, shall invalidate any order, decision, rule or regulation made, approved, or confirmed by the commission. [1959 c.252 §18]