  We calculate the corrections to the Casimir force between two metals due to
the spatial dispersion of their response functions. We employ model-independent
expressions for the force in terms of the optical coefficients. We express the
non-local corrections to the Fresnel coefficients employing the surface
$d_\perp$ parameter, which accounts for the distribution of the surface
screening charge. Within a self-consistent jellium calculation, spatial
dispersion increases the Casimir force significatively for small separations.
The nonlocal correction has the opposite sign than previously predicted
employing hydrodynamic models and assuming abruptly terminated surfaces.

Quantum Physics