assessor (n.)

late 14c., "assistant or adviser to a judge or magistrate," from Old French assessor "assistant judge, assessor (in court)" (12c., Modern French assesseur) and directly from Latin assessor "an assistant, aid; an assistant judge," in Late Latin "one who assesses taxes," literally "a sitter-by, one who sits by (another)," agent noun from past participle stem of assidere "to sit beside" (see assess). From 1610s as "one who assesses taxes." Milton uses it in the literal Latin sense in "Paradise Lost," calling Christ the Assessor of God's throne.