  We explore the physics of supersymmetric Janus gauge theories in four
dimension with spatial dependent coupling constants, e^2 and theta. For the 8
supersymmetric case, we study the vacuum and BPS spectrum, and the physics of a
sharp interface where the couple constants jump. We also find less
supersymmetric cases either due to additional expressions in the Lagrangian or
to the fact that coupling constants depend on additional spatial coordinates.
