ASSESSOR. — He is the one who advises and assists the judge in the study and decision of a case. According to Roman Republican law, the intervention of the assessor—also called *comes*, *iuris studiosus*, or *consiliarius*—was not at all obligatory and was left to the judge’s discretion from case to case. Later, especially in the imperial provinces, the office of assessor became a permanent institution.
In canon law, the assessor had the role of consultant, summoned when necessary to clarify points in a specific controversy (c. 11, *de rescriptis*, I, 3, in VI). The current Code maintains this understanding, as it (can. 1575) permits a single judge—not a collegial tribunal—to be assisted by no more than two assessors, chosen from among the synodal judges, with a consultative vote. The assessor takes an oath in accordance with can. 1622 and is bound to official secrecy under can. 1623.
The term *assessor* is also applied to the first-ranking official of the three Apostolic Congregations (the Holy Office, the Consistorial Congregation, and the Congregation for the Oriental Church) that have the Pope as their prefect (v. COMMISSIONI PONTIFICE). This office is equated in rank, duties, and privileges with the secretaries of the other Congregations (cf. the Constitution *Ad incrementum decoris* of Pius XI, 16 August 1934).
In Italian law, the term *assessore* refers to the members of the municipal council; from 1931 to 1945, it was also applied to the five lay judges of the *Corti d’Assise*.