The Maxwell–Garnett class of effective medium model applies if a representative cell can be found whose polarization vanishes upon insertion in the effective medium. For an anisotropic composite with randomly distributed ellipsoidal particles aligned along the principal axis, this leads to electrostatic restraints on the shape of such cells. It is shown that the cell boundary must have different depolarization factors to the inclusion within the cell. Practice is to equate them. A new physically correct ellipsometric modeling routine still with only two fitting parameters is demonstrated. ©1997 American Institute of Physics.