Step 1: Understand the question.
What is the main job of an arbitrator?
Step 2: Recall what arbitration is.
Arbitration is a way to settle disputes outside court. The arbitrator presides over the process.
Step 3: Define the arbitrator's role.
An arbitrator is a neutral third party who hears both sides, looks at the evidence, and gives a decision called an award that binds the parties.
Step 4: Eliminate the others.
An arbitrator does not act as an advocate for one party, does not just give non-binding suggestions to a court, and does not represent the state in criminal cases.
Step 5: Conclude.
The arbitrator is a neutral third party who gives a binding decision.
Answer: To serve as a neutral third party who renders a binding decision.