Judges are considered to be the leaders of one of the three branches of government, the Judiciary. In liberal democracies with Rule of law, judges are required to be impartial and not influenced by outside factors.
In some Civil law jurisdictions with inquisitorial systems, judges go to special schools to be trained after graduating with a Law degree from a university; after such training they often become investigating magistrate. In Common law countries, judges usually operate according to the Adversarial system of Justice under the applicable rules of Civil procedure, and usually are not trained separately from lawyers. In the Law of the United States, judges are generally appointed or elected from among practicing attorneys.
In the common law system, when there is a Jury trial in the trial courts, the Jury generally decides questions of fact (guilt or innocence, whether a party was negligent, what the amount of damages should be, etc.) while the judge decides questions of law (under common-law systems, one of the judge's most important power is Jury instructions). In the United States, bench trials and summary judgments are situations in which the judge decides issues of both law and fact.
Historically, in Europe in the Middle Ages, juries often stated the law by Consensus or Majority and the judge applied it to the facts as he saw them. This practice generally no longer exists.
In Finland, there are two kinds of judges in district courts: a legally-trained judge functions as the president of the court, while judges elected for a four-year term from the population, without any special legal training, serve as lay members of the court. Judges in special courts and apellate courts are always legally trained. Lay judges do not function like a common-law jury. In the usual case, three lay judges in district courts hear criminal cases in cooperation with a legally trained judge, each judge - legally trained or not - having an individual vote. Civil cases, however, are heard exclusively by legally trained judges.
In many parts of the world, judges wear long robes (usually in Black or red) and sit on an elevated platform during trials (known as the bench). In some countries, especially Britain, judges also wear wigs. Contrary to popular belief, the long wig usually assocated with judges is not worn every day, but is reserved for ceremonial occasions. A short wig resembling but not identical to a barrister's wig is worn in court.
American judges usually always wear simple black robes and use gavels to keep order in the courtroom. However, in some Western states, like California, judges did not always wear robes and instead wore everyday clothing. Today, the Maryland Court of Appeals is the only State supreme court that deviates from the standard uniform; its seven judges wear red robes.
In the People's Republic of China, judges wore regular street clothes until 1984, when they began to wear military-style uniforms, which were intended to demonstrate authority. These uniforms were replaced in 2000 by black robes similar to those worn in the rest of the world.
The justices of the supreme courts usually hold higher offices than the Justice of the Peace, a judge who holds Police Court in some jurisdictions and who typically tries small claims and misdemeanors. However, the state of New York inverts the usual order, with the Supreme Court of the State of New York being the trial court, and the Court of Appeals being the highest court; thus, New York trial judges are called "justices," while the judges on the Court of Appeals are "judges." New York judges who deal with trusts and estates are known as "surrogates."
In England and Wales, judges of the higher courts are addressed as "My Lord" or "My Lady" and referred to as "Your Lordship" or "Your Ladyship." Circuit Judges are addressed as "Your Honour" and all lower judges, magistrates, and chairs of tribunals are addressed as "Sir" or "Madam." Magistrates were at one time addressed as "Your Worship," mainly by solicitors, but this practice is nearly obsolete. Masters of the High Court are addressed as "Master." When a judge of the High Court who is not present is being refered to they are described as "Mr./Mrs. Justice N" (written N J). In the House of Lords, judges are called Law Lords and sit as peers.
In France, the presiding judge of a court is addressed to as "Mr./Mrs. President" (Monsieur le président/Madame le président).
Judges of courts of specialized jurisdiction (such as Bankruptcy courts or Juvenile courts) were sometimes known officially as "referees," but the use of this title is in decline. Judges sitting in courts of equity in Common law systems are called "Chancellors."