English Noun leading case (plural leading cases) (law) A reported decision which has come to be regarded as settling the law of the question involved. 1857, Austin Abbott, Reports of Practice Cases:It is remarkable , that in the leading case cited as the foundation of the whole doctrine See also precedent References “leading”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.Wikiwand - on Seamless Wikipedia browsing. On steroids.