The dielectric tensor ε of cubic electro-optical materials polarized along a cube edge is of the same form as ε for magneto-optical materials except that the former is symmetric and the latter anti-symmetric. The polar, longitudinal, and transverse characteristic matrices necessary to solve multi-layer thin film electro- or magneto-optical scattering problems are given in terms of a symmetry parameter σ = ±. Using a λ/4 ZnS film in the transverse orientation and placed on an E-mirror, and a multi-layer dielectric structure consisting ofRdouble λ /4 layers plus an additional λ /4 film, phase shifts of 180° are predicted forR= 3 and a controlling electric field of ∼ 1 volt/cm.