Английский Этимологический словарь - cop (v.)

- 1704, northern British dialect, "seize," perhaps from M.Fr. caper "seize, to take," from L. capere "to take;" or from Du. kapen "to take," from O.Fris. capia "to buy." Cop out is Amer.Eng. c.1967, probably from cop a plea (c.1925) "plead guilty to lesser charges."