A special master or master in chancery is an individual appointed by the court to assist with some part of a lawsuit, such as discovery—depositions, written questions, and production of documents—and to make recommendations to the judge on how to resolve related disputes. Courts have held that discovery questions that require extensive examination of highly technical and complex documents by a person having both a technical and a legal background may constitute an exceptional condition sufficient to justify the appointment of a master to supervise such discovery.

In Arizona, a special master, sometimes referred to as a master in chancery, is an individual appointed by the court to assist in complex aspects of a lawsuit, particularly in the discovery process. This role involves overseeing depositions, managing the exchange of written questions and answers, and handling the production of documents. The appointment of a special master is typically justified under exceptional conditions where the case involves highly technical or complex documents that require the expertise of someone with both technical knowledge and a legal background. Arizona Rule of Civil Procedure 53 provides the framework for the appointment, powers, duties, and compensation of special masters. The rule allows a court to appoint a special master when the issues are complicated and it would be beneficial to have an expert assist in resolving discovery disputes or other procedural matters. The special master reports to the judge, offering recommendations on how to proceed with the case. The use of a special master is intended to streamline the legal process and provide specialized knowledge that the court may not possess, thereby enhancing the efficiency and effectiveness of the judicial system.