  We use linear response techniques to develop the previously proposed
relativistic ideal fluid limit with a non-negligible spin density. We confirm
previous results and obtain expressions for the microscopic transport
coefficients using Kubo-like formulae and buld up the effective field theory
from the computed correlation functions. We also confirm that polarization
makes vortices aquire an effective mass via a mechanism similar to the
Anderson-Higgs mechanism in superconductors. As speculated earlier, this could
stabilize the ideal hydrodynamic limit against fluctuation-driven vortices
