In general, a circuit judge conducts trials, makes judgments, and must constantly research and stay abreast of changes in the law. Conducting trials requires a judge to hear disputes and decide who should win a case. To make decisions in a trial, a judge must know the rules for conducting a trial. He or she must also understand the laws that control a particular subject matter. A judge must also have the skills to put decisions in writing.
Historically, in the U.S., state and federal court trial judges, for example, had to travel routinely to numerous locations in a specific geographical region to hear cases. People referred to the various locations with the region as a circuit; this is how the term circuit judge came about. Today a circuit judge is more likely to be assigned to just one courthouse.
To perform judicial duties, a circuit judge must be knowledgeable about rules of procedure which control how cases flow through the court. The purpose of these rules is to ensure fairness in the trial process. A judge must understand how to apply these rules when lawyers file conflicting motions or disagree on the meaning or interpretation of the rules. Further, higher courts often make decisions on how to apply a certain rule, which can determine how a circuit court judge must apply a particular rule. This requires a judge to remain vigilant about any decisions that control how rulings on certain matters must be made.
A circuit judge must also know how to apply the rules of evidence to a case. These rules control what types of evidence — including testimony, documents, property — a judge may admit into court. Conversely, the rules may require a judge to exclude certain evidence. The rules of evidence are also constantly changing.
Understanding the rules of procedure and the rules of evidence allows a circuit judge to conduct trials. A circuit judge must conduct a trial in a neutral manner, which means the judge cannot show bias against or for one party. The various rules that regulate a trial help a judge to remain evenhanded.
A circuit judge is also required to write specific types of legal documents such as a judgment or an order. A judgment contains the factual findings of the court and the reasoning to support the court’s decision in a particular case. An order may also contain findings of fact; it is usually more concise than a judgment, however. A judge structures these documents in a specific format as required by the rules of the jurisdiction.