A judge is a person who presides over court proceedings, either alone or as a part of a panel of judges. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions. The judge is supposed to conduct the trial impartially and, typically, in an open court. The judge hears all the witnesses and any other evidence presented by the barristers or solicitors of the case, assesses the credibility and arguments of the parties, and then issues a ruling on the matter at hand based on their interpretation of the law and their own personal judgment. In some jurisdictions, the judge's powers may be shared with a jury. In inquisitorial systems of criminal investigation, a judge might also be an examining magistrate.
Judges may work alone in smaller cases, but in criminal, family and other significant cases, they work in a panel. In some civil law systems, this panel may include lay judges. Unlike professional judges, lay judges are not legally trained, but unlike jurors, lay judges are usually volunteers and may be politically appointed. Judges are often assisted by law clerks, referendaries and notaries in legal cases and by bailiffs or similar with security.
American judges frequently wear black robes. American judges have ceremonial gavels, although American judges have court deputies or bailiffs and contempt of court power as their main devices to maintain decorum in the courtroom. However, in some of the Western United States, like California, judges did not always wear robes and instead wore everyday clothing. Today, some members of state supreme courts, such as the Maryland Court of Appeals wear distinct dress. In Italy and Portugal, both judges and lawyers wear particular black robes.
In Pakistan, judges of the Supreme Court and the high courts are addressed as Your Lordship or My Lord or Lordship and Your Ladyship or My Lady, a tradition directly attributable to England. There is some resistance to this on religious grounds but more or less continues till this day. In lower courts, judges are addressed as sir, madam or the Urdu equivalent Janab or Judge Sahab.
In the Courts of England and Wales, Supreme Court judges are called Justices of the Supreme Court. Justices of the Supreme Court who do not hold life peerages are now given the courtesy style "Lord" or "Lady." Justices of the Supreme Court are addressed as "My Lord/Lady" in court. In the law reports, the Justices of the Supreme Court are usually referred to as "Lord/Lady N", although the Weekly Law Reports appends the post-nominal letters "JSC" (e.g. "Lady Smith JSC"). The President and Deputy President of the Court are afforded the post-nominal letters PSC and DPSC respectively. Only experienced barristers or solicitors are usually appointed as judges.
When a Justice of the High Court who is not present is being referred to they are described as "Mr./Mrs./Ms. Justice N." In legal writing, the post-nominal letter "J" is used to denote a Justice (male or female) of the High Court: for example, Smith J. Masters of the High Court are addressed as "Master". Insolvency and Companies Court judges in the High Court are addressed as “Judge”.
In Northern Ireland, the equivalent to a circuit judge is a county court judge, and they are addressed and titled the same way as a circuit judge is in England and Wales. The senior county court judges assigned to the county court divisions of Belfast and Derry have the titles of Recorder of Belfast and Recorder of Londonderry (or Derry) respectively, but are addressed the same as other county court judges. A district judge sitting in the County Court is addressed as "Your Honour".
The judges of the Supreme Court of the United States, and the judges of the supreme courts of several US states and other countries are called "justices". Justices of the Supreme Court of the United States and Justices of other courts are addressed as "Justice (name)." The Chief Justice of the United States is formally addressed as "Mr. or Madam Chief Justice" but also may be identified and addressed as "Chief Justice (name)".
Subordinate or inferior jurisdiction judges in US legal practice are sometimes called magistrates, although in the federal court of the United States, they are called magistrate judges. Subordinate judges in US legal practice who are appointed on a case-by-case basis, particularly in cases where a great deal of detailed and tedious evidence must be reviewed, are often called "masters" or "special masters" and have authority in a particular case often determined on a case by case basis.
Unlike many civil law countries which have some courts on which panels of judges with nearly equal status composed of both legally trained professional judges and lay judges who lack legal training and are not career judges, the United States legal system (like most Anglo-American legal systems) makes a clear distinction between professional judges and laypeople involved in deciding a case who are jurors who are part of a jury. Most but not all US judges have professional credentials as lawyers. Non-lawyer judges in the United States are often elected, and are typically either justices of the peace or part-time judges in rural limited jurisdiction courts. A non-lawyer judge typically has the same rights and responsibilities as a lawyer who is a judge holding the same office and is addressed in the same manner.