  We present Maxwell equations with source terms for the electromagnetic field
interacting with a moving electron in a spin-orbit coupled semiconductor
heterostructure. We start with the eight--band ${\bm k}{\bm p}$ model and
derive the electric and magnetic polarization vectors using the Gordon--like
decomposition method. Next, we present the ${\bm k}{\bm p}$ effective
Lagrangian for the nonparabolic conduction band electrons interacting with
electromagnetic field in semiconductor heterostructures with abrupt interfaces.
This Lagrangian gives rise to the Maxwell equations with source terms and
boundary conditions at heterointerfaces as well as equations for the electron
envelope wave function in the external electromagnetic field together with
appropriate boundary conditions. As an example, we consider spin--orbit effects
caused by the structure inversion asymmetry for the conduction electron states.
We compute the intrinsic contribution to the electric polarization of the
steady state electron gas in asymmetric quantum well in equilibrium and in the
spin Hall regime. We argue that this contribution, as well as the intrinsic
spin Hall current, are not cancelled by the elastic scattering processes.
