Observational Evidence against Birefringence over Cosmological Distances

We show that recent radio and optical observations of polarized radiation from well-resolved high redshift quasars and radio galaxies rule out the cosmological rotation of the plane of polarization claimed recently by Nodland and Ralston Phys. Rev. Lett. 78, 3043 (1997). A least squares fit to the radio data has a slope only 2% of their claimed effect.