An adjudicator is someone who presides, judges, and arbitrates during a formal dispute or competition. They have numerous purposes, including preliminary legal judgments, to determine applicant eligibility, or to assess contenders' performance in competitions.

An example is a person who makes a preliminary judgment as to an unemployment insurance claim. An adjudicator makes an initial decision to keep a case from going to court. Although the adjudicator's decision does not have legal weight, the adjudicator has rendered a decision. Although a case can be appealed to a judge, the adjudicator's decision is frequently accepted as the same as what a judge would make, keeping many time-consuming cases out of the court system.

The term is used to refer to a panel of judges in the process of considering security clearances for the United States government. The panel reviews information from a background investigation and a polygraph and decides whether to grant the clearance. Adjudicators can be a medical review board that makes disability and retirement benefit decisions for Federal employees and military personnel. Adjudicators also exist for immigration benefits.^[1]

An adjudicator (often referred to as a "judge", "umpire", "arbiter", or more archaically as a "daysman"^[2]), is a person who gives a critical evaluation of performances in competitions, festivals or talent shows, resulting in the award of marks, medals or prizes.

In BP debate, an adjudicator^[3] weighs arguments and decides rankings in the house. There are different types of adjudicators, each with their respective duties and levels of authority: chair, panelist, and trainee. In the event that the chair is the chief adjudicator of the tournament, they are referred to as "Speaker".

• Adjudicators Field Manual, United States Department of Homeland Security, Citizenship and Immigration Services