n.
One with special knowledge of a subject who is appointed or elected to assist a judge or magistrate in deciding a legal matter.
In the U.S., the term also designates an official who evaluates property for the purposes of taxation. Assessors were appointed in the late 19th century throughout Europe to try to limit the influence of the jury system, which had been introduced in the wake of the French Revolution. Assessors thus represented a return to the civil-law traditions of Europe. In Britain and the U.S., assessors came to be used in labour and maritime courts as well as in some other civil jurisdictions.