  The vertex correction for the electric current is discussed on the basis of
the Fermi-liquid theory. It does not alter the qualitative description of the
electric transport by the relaxation-time approximation in the case of the
normal state of high-Tc superconductors. The failure of the transport theory
employing the fluctuation-exchange (FLEX) approximation is pointed out. It
becomes manifest by considering the Ward identity for the fluctuation mode.
