Unconditional existence of densities for the Navier-Stokes equations with noise

The first part of the paper contains a short review of recent results about the existence of densities for finite dimensional functionals of weak solutions of the Navier--Stokes equations forced by Gaussian noise. Such results are obtained for solutions limit of spectral Galerkin approximations. In the second part of the paper we prove via a ``transfer principle'' that existence of densities is universal, in the sense that it does not depend on how the solution has been obtained, given some minimal and reasonable conditions of consistence under conditional probabilities and weak--strong uniqueness. A quantitative version of the transfer principle is also available for stationary solutions.