NKRUMAH AND ANOTHER v. MANU Defamation—Slander—Law applicable—Customary law or common law—Action between two Ghanaians—No indication that plaintiff subject to any system of customary law—No claim to have issue determined according to customary law—Courts Decree, 1966 (N.L.C.D. 84), para. 64 (1), Rule 6.