  We present optical spectropolarimetric and imaging polarimetric observations
of four high-redshift radio galaxies (HzRGs) obtained with the 10-m Keck I
telescope. A broad Mg II emission line is detected in the total and polarized
flux spectra of 3C 265 and 3C 277.2. The fractional polarization is high, and
both it and the position angle are constant with wavelength after accounting
for dilution by unpolarized starlight of the host galaxy, which can contribute
substantially. An extended unpolarized continuum similar to that observed in
other AGNs is also detected. Imaging polarimetry reveals a rough double-fan
morphology of the polarized light coincident with the extended aligned emission
regions, with the position angle essentially perpendicular to the radial
structure of the extended UV/optical emission, and with the degree of
polarization increasing with radius away from the nucleus. The radio jets lie
inside the extended emission regions and, like every radius, are roughly
perpendicular to the polarization PA. These results strengthen the view that
powerful radio galaxies would be called quasars if viewed from a proper
direction. Based on the polarimetric data presented in this paper and in
previous studies, scattering of radiation from an obscured quasar source
appears to be the preferred interpretation over jet-induced star formation for
explaining the alignment effect in HzRGs. Both electrons and dust can play a
major role in the scattering process. However, the lack of strong direct
evidence for either case, and our ignorance of the properties and distribution
of the scatterers in these galaxies make it very difficult to discriminate
between the two. Our data reveal a chance alignment of 3C 343.1 with a
foreground galaxy, which dominates the observed optical flux from the system.
