We study the stability of capillary hypersurfaces in a unit Euclidean ball. It is proved
that if the center of mass of the domain enclosed by the immersed capillary
hypersurface and the wetted part of the sphere is located at the origin, then the
hypersurface is unstable. An immediate result is that all known examples except the
totally geodesic ones and spherical caps are unstable. We also conjecture a
precise delineation of the stable capillary hypersurfaces in unit Euclidean
balls.