We argue that there exist two kinds of passive structures, a) one generated in the base b) the other transformationally derived by the structure preserving-rule of move-NP. Assuming a Case theory along the lmines of Chomsky (1978), we want to argue a) that some oblique Cases are assigned in the base b) that NP movement can move an oblique Case assigned in the base c) that movement should not be defined in terms of Case but in terms of Government.