  We investigate the appearance of Chern-Simons terms in electrodynamics at the
surface/interface of materials. The requirement of locality, gauge invariance
and renormalizability in this model is imposed. Scattering and reflection of
electromagnetic waves in three different homogeneous layers of media is
determined. Snell's law is preserved. However, the transmission and reflection
coefficient depend on the strength of the Chern-Simons interaction, and
parallel and perpendicular components are mixed.
