An arbitration is an informal hearing. That may be why attorneys believe that they can tell the arbitrator what they think they can prove through an expert at trial. Sometimes they ask the arbitrator to use his/her expertise as a substitute for expert evidence that should have been presented. An arbitration, as informal as if may be, is still a forum for litigating factual disputes. The arbitrator cannot speculate as to the brilliant testimony of an expert nor can s/he substitute his or her judgment on issues requiring expert testimony.