Officer of the court
In the United States, the generic term officer of the court (not to be confused with court officers) is applied to all those who, in some degree in function of their professional or similar qualifications, have a legal part—and hence legal and deontological obligations—in the complex functioning of the judicial system as a whole, in order to forge justice out of the application of the law and the simultaneous pursuit of the legitimate interests of all parties and the general good of society.
They can be divided into the following functional groups; in most case various synonyms and parallels exist as well as a variety of operational variations, depending on the jurisdiction and the changes in relevant legislation:
Court proper 
Foremost those who make the decisions that determine the course of justice and its outcome:
- judges, magistrates and arbitrators
- attorneys for each party - the Supreme Court of the United States held in Ex parte Garland that "Attorneys and counselors are not officers of the United States; they are officers of the court, admitted as such by its order upon evidence of their possessing sufficient legal learning and fair private character." (in some jurisdictions - such as England and Wales - independent advocates such as barristers are not officers of the court).
Investigation and expertise 
These are, like the accidental witness, though not in chief of accidental access to relevant information but through their skills, experience and equipment, used to provide information to the actual decision makers above
- coroners, medical examiners, and other medical experts
- other judicial experts in various fields, such as state certified appraisers, certified public accountants and other professionally licensed or certified persons retained by the parties to give expert advice, the testimony and exhibits of which is admitted by the Court.
Services to the parties 
- Bail bondsmen, who may however undertake action to capture an absconding client
- Interpreters/translators are generally considered officers of the court. They render their services to the parties in the interests of the court proceedings. There are interpreters who may be employed on a permanent basis by courts to act as interpreters when called upon, e.g. International Court of Justice and the European Court of Justice. In some jurisdictions interpreters may also be deemed as officers of the court pro tempore. Court interpreters and translators have an absolute ethical duty to tell judges the truth and avoid evasion.
- Court Appointed Special Advocates in some jurisdictions are considered officers of the court.
- Process servers carry out service of process. In some jurisdictions they are appointed by a court and are considered appointed officers of the court.