  We consider the Fokker--Planck equations with irregular coefficients. Two
different cases are treated: in the degenerate case, the coefficients are
assumed to be weakly differentiable, while in the non-degenerate case the drift
satisfies only the Ladyzhenskaya--Prodi--Serrin condition. Using Trevisan's
superposition principle which represents the solution as the marginal of the
solution to the martingale problem of the diffusion operator, we establish
quantitative stability estimates for the solutions of Fokker--Planck equations.
