  We investigate the Pauli blocking factor in quantum pumps using Floquet
formalism. Even though the time dependent potentials in quantum pumping can not
only cause inelastic scatterings but also break the micro-reversibility, i.e.
$T^+(E',E) \neq T^-(E,E')$, the Pauli blocking factor is unnecessary when the
scattering process through the scatterer is coherent. The well defined
scattering states extending from one reservoir to the others form a complete
non-orthogonal set. Regardless of the non-orthogonality one can obtain the
pumped currents using the field operator formalism. The current expression
finally obtained do not contain Pauli blocking factor.
