  We present an update of the cosmic polarization rotation (CPR) constraint
from the recent SPTpol measurements of sub-degree B-mode polarization in the
cosmic microwave background (CMB) of 100 square degrees of sky. Our previous
CPR fluctuation constraint from the joint ACTpol-BICEP2-POLARBEAR polarization
data is 23.7 mrad (1.36{\deg}). With new SPTpol data included, the CPR
fluctuation constraint is updated to 17 mrad (1{\deg}) with the scalar to
tensor ratio r = - 0.05 +- 0.1
