A judge–advisor system (JAS) is a type of advice structure often studied in advice taking research, a subset of decision-making in the social sciences. The two roles in a JAS are the judge and advisor roles. The judge is the decision maker who evaluates information concerning a particular decision and makes the final judgment on the decision outcome. The advisor is an individual who provides advice, information, or suggestions to the judge. A key component of the dynamics in a JAS is the differentiation between the two roles in that while the advisor provides input to the decision, actual decision-making power resides solely with the judge. This one person decision power differentiates the JAS and related models such as Hollenbeck's Hierarchical Decision-Making Team model from more widely studied models where the final decision is mutually decided upon by the team as a whole.

While JASs can be most easily thought of as between superiors and subordinates (such as in student–advisor or worker–manager relationships), differential social or power standings are not necessary. All that is required is that only one individual (the judge) has the final say in the decision outcome; all other input given to the judge may be taken under consideration but need not be acted on. Therefore, even a situation where a friend receives advice from a peer can be considered a JAS.

A judge is a person who presides over court proceedings, either alone or as 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 in an open court. The judge hears all the witnesses and any other evidence presented by the parties of the case, assesses the credibility and arguments of the parties, and then issues a ruling on the matter at hand based on his or her interpretation of the law and his or her 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.

A variety of traditions have become associated with the rank or 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.

A system (from Latin systēma, in turn from Greek σύστημα systēma, "whole compounded of several parts or members, system", literary "composition") is a set of interacting or interdependent components forming an integrated whole.

A system is a set of elements (often called 'components' ) and relationships which are different from relationships of the set or its elements to other elements or sets.

Fields that study the general properties of systems include systems theory, cybernetics, dynamical systems, thermodynamics and complex systems. They investigate the abstract properties of systems' matter and organization, looking for concepts and principles that are independent of domain, substance, type, or temporal scale.

Most systems share common characteristics, including:

The term system may also refer to a set of rules that governs structure and/or behavior.

The word system in its meaning here, has a long history which can be traced back to Plato (Philebus), Aristotle (Politics) and Euclid (Elements). It had meant "total", "crowd" or "union" in even more ancient times, as it derives from the verb sunìstemi, uniting, putting together.