  The back-reaction effects for the spinning charge moving through the constant
homogeneous electromagnetic field are studied in the context of the mass-shift
(MS) method. For the g=2 magnetic moment case we find the (complex) addition to
the classical action. Its dependence on the integrals of the unperturbed motion
proves to be important in determination of the orbital radiation effects and
could assist in understanding the radiation polarization (RP) phenomenon.
