Sometimes, a disputant decides to represent himself in the arbitration, called pro-se.
Just as in a courtroom setting, this is not a good idea, since the party isn't likely to be familiar with the arbitration process, the kind of evidence to be presented, the applicable rules, and so on.
What's worse, most of the cases I've seen are an individual against a large corporation. The fact that the resources are so stacked against the pro-se party makes matters even worse and can tip the balance in the corporation's favor when the evidence does not support such a condition.
I have had parties self-represent themselves, and the problem it presents to the arbitrator is that the unrepresented person often will not know to challenge a piece of evidence that should be challenged, or not present evidence that exists and would be helpful to them.
The standard intelligence is that the arbitrator(s) should let the parties do what they are going to do, without interfering or trying to present a case or challenge either side. But it is frustrating when we see that the case is being mishandled in that way.
In such a circumstance, and in an attempt to know the truth, if a key piece of evidence is not questioned by the pro-se party, I will ask a few clarifying questions that help define the differences between the two sides.
In my opinion, the best suggestion any arbitrator can offer to a pro-se party, since the stakes can be high, is to recommend in the strongest terms that they engage an attorney, or at the least, bring an adviser who can help present their case.