An American judge talks to a lawyer.
A judge or justice is an official who presides over a court. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions.
Judges in the legal system
There are significant differences between the role of a judge in the common law system descended from British practice, and civil law systems descendant from continental European judicial practice. The descriptions below are necessarily archetypical. Details vary from judicial system to judicial system. In many cases, the judicial systems have experienced convergent evolution, expressly or unconsciously adopting similar practices or operating in a manner that minimizes the impact of formal differences between the archetypical role of each system's judges.
For example, while common law judicial procedure generally contemplates a single evidentiary trial, many cases are actually resolved through testimony taken from witnesses in isolated depositions prior to trial that support written presentations to a judge. Similarly, while civil law judges must have some statutory point of departure for their legal rulings, there are accepted methods of legal reasoning that often afford them greater latitude to fit the law to the circumstances of an unusual case then a stark statement of the underlying principles of the system would suggest. This can serve a purpose similar to the common law method of legal reasoning known as stare decisis.
Judges in civil law systems
In most 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 magistrates. However, the inquisitorial system is not used in all civil law jurisdictions; it is primarily in use in countries of Southern Europe that were influenced by Napoleon's Code Napoleon, such as France, Italy, Spain, Portugal etc. In Northern Europe, the adversarial system is predominant in criminal matters. Nevertheless, judges in both Northern and Southern Continental Europe generally do not have backgrounds as practicing attorneys (or advocates), even though they are legally trained.
In the civil law system, serious matters are almost always decided at the trial level by at least three judges, and sometimes more, often in combination with lay persons in serious criminal manners, although one of those judges may take the lead in gathering evidence in a case. In civil law systems typically only the equivalent of U.S. small claims and misdemeanors are handled by a single trial judge.
For example, in Finland and Sweden, 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. In Sweden, the same is true for the appellate courts. 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. However, in some jurisdictions, such as Denmark, criminal cases in severe matters, such as homicide, require a trial by jury, where the jury decides upon the issue of mens rea. Issues of law – and also the assessment of what has factually been proven to have taken place – is the responsility of the judge, who guides the jury by means of a jury instruction. Civil cases, however, are heard exclusively by legally trained judges.
In civil law practice, appeals are usually decided by a panel of multiple judges. State courts can be called district courts. The highest appellate court in a civil law jurisdiction, often translated "supreme court" in English, is typically organized more like an intermediate appellate court in common law practice, in that decisions are usually made by a panel of judges that does not include all judges who are a member of that court. Also unlike common law practice, judges are typically assigned to appeals in the highest appellate court based on specialties in a particular type of law, rather than at random. Typically the only appellate court in a civil law system in which all members of the court will typically decide a case that will operate in a civil law country is the constitutional court, if any.
Non-judges with judicial power
Certain non-judges are vested with judicial power by virtue of their political or religious office, or their position as a responsible government employee.
In Japan, police officers can order punishments for minor offenses without approval from a judge. In U.S. military law, military officers can dispense justice for minor military law infractions without holding a court-martial, and also preside over courts-martial involving more serious offenses. A number of jurisdictions give mayors of municipalities judicial authority similar to a justice of the peace or magistrate. Many courts with probate jurisdiction give court clerks quasi-judicial authority as "registrars" of the court. Members of county commissions and city councils in the United States often have quasi-judicial authority in zoning matters. And, legislators sometimes sit in a judicial capacity, such as when they rule on impeachment charges of governmental officials, and in the United Kingdom, when law lords, who are officially members of the House of Lords, a primarily legislative body, hear appeals in legal cases.
Historically, in the United Kingdom, certain matters, such as annulments of marriages and division of personal property of deceased persons, were the responsibility of ecclesiastical courts, in which clergy presided. Many countries, such as Israel and Pakistan and Iran, continue to have religious courts, particularly in matters of family law, that operate in addition to their ordinary courts with full authority to enter legally binding decisions. Other countries, such as Afghanistan under its newly adopted constitution, have a unitary court system in which some judges have primarily secular training, while others judges have primarily religious training.
Often parties in contractual relationships with each other enter into "arbitration agreements" which vests quasi-judicial authority to resolve disputed between the parties in a non-judge chosen by mutually agreed means. Sometimes these persons are legally trained, and sometimes they are not, but have some relevant subject matter expertise. Civil justice in the Roman Empire, which provided some of the foundational doctrines for Western systems often handled civil disputes through an arbitration-like mechanism. Courts can typically be called upon to enforce a final decision rendered by an arbitrator pursuant to an arbitration agreement if necessary.
Power of judges
In common law countries, such as the United States, and those with roots in the Commonwealth of Nations, judges have a number of powers which are not known to exist, or are not acknowledged to exist, in civil law legal systems, which collectively make the judiciary a more powerful political force than in civil law countries.
One of these powers is the "contempt of court" power. In a common law system, a judge typically has the power to summarily punish with a fine or imprisonment any misconduct which takes place in the courtroom, and to similarly punish violations of the court's orders, after a hearing, when they take place outside the courtroom. This power, in turn, may be used by common law judges to enforce orders for injunctive relief, which is a court order to take or refrain from taking some particular act, directed at the individual who must do so. This power is a vestige of authority that members of the nobility had when they personally presided over disputes between their subjects. It has the effect of giving common law country judges great power to fashion remedies, such as school desegregation orders and restraining orders directed at individuals. Civil law judges, in contrast, outside of specialized courts with narrowly delineated powers, generally lack contempt power or the power to impose injunctive relief.
Another power of every judge in the United States, generally right down to the level of the magistrate, is the power to declare a law unconstitutional and invalid, at least as applied in a particular case. In contrast, most civil law countries limit this power to a special constitutional court, and all other judges are required to follow the enacted laws, even if the judge personally believes those laws to be unconstitutional, in the absence of an order from the constitutional court. However, if a person believes that a law applied against them in court is unconstitutional, they can apply for consideration in the constitutional court and, if the law is indeed declared unconstitutional, file an appeal against the ruling based on the now-invalidated law.
Similarly, in the common law system, cases in which the government administration is at issue, known as public law cases, for example, suits claiming violations of civil rights by government officials, are often heard by the same judges who handle criminal cases and disputes between private individuals. In contrast, in civil law countries, only designated judges or quasi-judges (such as the Conseil d'État in France) can hear public law cases, and ordinary judges can hear only criminal cases and cases involving private parties.
Judges in a common law system are also empowered to make law guided by past precedent, or to choose to ignore past precedent as no longer applicable, based on a concept known as "stare decisis" ("to stand by what has been decided"), in cases where no statute or prior case clearly mandates a particular result, and in cases where past precedents, for some reason, no longer appear to provide firm guidance as to the current state of the law. For example, in a case of "first impression" which has never arisen in a publicly reported case in a state, a judge must choose which rule will apply, usually informed by decisions which have been made in similar cases in other jurisdictions and based on the public policies involved. Judges in civil law systems, in contrast, are strictly forbidden from "making law" and, as a general rule, are not bound by or even encouraged to refer to precedents established in prior similar cases.
Civil law judges, likewise, have some powers not usually held by common law judges. Most importantly, a common law judge is usually required to base a decision almost exclusively on the evidence provided by the parties to a case during the course of a trial, or a hearing, or in documents filed with the court. In contrast, a civil law judge frequently has the authority to investigate the facts of a case independently of evidence provided by the parties to that case, in what is known as an "inquisitorial" role.
All judges must sign a judicial oath which is a fiduciary undertaking or a promise of duty of care. Yet the moment it is signed, the judge is protected with judicial immunity which prevents anyone from testing the obligation the judge undertook in the oath. Arguments against the judicial immunity say this law is allowing judges a special method of escape for claims for breach of fiduciary duty which is something no other fiduciary apart from politicians can obtain.
Oversight of judges
Federal judges in the United States (except those who have recess appointments) serve life terms for their period of "good behavior." Once appointed, state judges in the United States usually serve terms for a fixed period of years, after which they must be re-elected, face a retention election, or face reappointment by an appropriate authority. The law governing judicial elections in the United States is in flux with the general tendency being to discard historical limitations on the ability of a judge to campaign based upon judicial philosophy.
Most judicial systems in the United States have procedures for investigating breaches of judicial ethics and disability. Lapses of judicial ethics include matters such as taking bribes, open defiance of a binding court order, ruling upon a case in which the judge has a personal interest, failure to account for court funds, failure to conduct court proceedings with a suitably judicial demeanor, harassment of judicial employees or a judge's conviction of a serious offense unrelated to judicial service. Disability complaints often involve allegations that a judge is beginning to show symptoms of alcoholism, dementia or an inability to stay awake.
Complaints about a judge's judicial ethics or disability may ordinarily not contest the merits of the determination made by the judge, which can only be contested in the appellate process. Judges in the United States generally have absolute immunity for personal liability in the form of money damages for their discretionary judicial acts.
Almost every state and the federal government provides the legislature with the authority to remove a judge for cause in a quasi-judicial impeachment proceeding in which the legislative body hears evidence and renders a super-majority verdict limited to removal from office. Often the standard is "high crimes and misdemeanors" or failure to engage in "good behavior" while in office.
Many state judicial systems also have either a special commission or board charged with investigating alleged lapses of judicial ethics or disability, or vest that power in their highest court, usually a state supreme court. Such determinations may be appealed to the Supreme Court of the United States only to the extent that they involve the final decision of a state court system and pose a federal law question.
Some violations of judicial ethics, such as taking bribes or converting public funds, are also federal or state crimes investigated and prosecuted by the appropriate prosecutor.
In the federal system, there is no outside grievance body with the authority to discipline a U.S. Supreme Court justice. The U.S. Supreme Court has supervisory authority over the entire federal judiciary, in addition to its appellate responsibilities, and it has used this authority to establish certain procedures for investigating and addressing lapses of judicial ethics by federal judges.
In Canada, Justices (Justices of Peace) are appointed provincially to preside over minor cases, while Judges are appointed federally. Neither can be removed from office until they reached the retirement age of 65, 70 or 75 (depending on the type of appointment) unless they are found to have been in serious misconduct, in which case, the House of Commons and Senate (federally appointed) or the Judicial Council (provincially appointed) can pass a motion to remove a judge/justice from office. 
Symbols of office
Being a judge is usually a prestigious and solemn position in society. A variety of traditions have become associated with the occupation.
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 in the Commonwealth of Nations, judges sometimes wear wigs. The long wig often associated with judges is now reserved for ceremonial occasions, although it was part of the standard attire in previous centuries. A short wig resembling but not identical to a barrister's wig would be worn in court. This tradition, however, is being phased out in Britain in non-criminal courts.
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 Western 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 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.
In Oman, the judge wears a long stripe (Red, Green and White), while the attorneys wear the black gown.
In the United States, a judge is addressed as "Your Honor" or "Judge" when presiding over the court. The judges of the Supreme Court of the United States, and the judges of the supreme courts of several U.S. states and other countries are called "justices".
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 most important 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 guardianships, trusts and estates are known as "surrogates".
A "senior judge" in U.S. practice, is a retired judge who handles selected cases for a governmental entity while in retirement on a part-time basis.
Subordinate or inferior jurisdiction judges in U.S. legal practice are sometimes called magistrates, although in the federal court of the United States, they are called "magistrate judges". Subordinate judges in U.S. legal practice 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.
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 (such as judges in the equity courts of the U.S. State of Delaware) are called "Chancellors".
Individuals with judicial responsibilities who report to an executive branch official, rather than being a part of the judiciary, are often called "administrative law judges" in U.S. practice and commonly make initial determinations regarding matters such as eligibility for government benefits, regulatory matters, and immigration determinations.
Judges who derive their authority from a contractual agreement of the parties to a dispute, rather than a governmental body are called arbitrators, and typically do not receive the honorific forms of address, and do not have the symbolic trappings, of a publicly appointed judge.
In England and Wales (and much of the Commonwealth) 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 are still addressed as "Your Worship" in Australia, South Africa and Canada, mainly by solicitors, but this practice in other Commonwealth countries 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 referred 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), in Germany as "Mr./Mrs. Chairman (Herr Vorsitzender/Frau Vorsitzende)