Explanation:

One drawback to the process is the lack of a formal evidence process. This lack means you are relying on the skill and experience of the arbitrator to sort out the evidence, rather than a judge or jury. No interrogatories or depositions are taken, and no discovery process is included in arbitration.

The lack of a formal appeals process and the—usually—binding nature of the process also draws detractors. If you are a party to binding arbitration and you want to protest the decision of the arbitrator, you may not be able to do so unless there is some reason to believe the arbitrator acted with malice or was biased.

Mandatory arbitration clauses in consumer contracts, employment contracts, and nearly every online agreement that you click "Accept" often work in favor of the company rather than the employee or consumer. 

Arbitrators may not be unbiased. If an arbitrator has a history of siding against one side in a dispute, that arbitrator may not be chosen, against one who has a history of being impartial to either side. 

Finally, the fact that arbitration hearings are not public may put one side at a disadvantage.