Abstract
The properties of a disordered solid with spin-orbit coupling to impurities are studied in the frame of the 2+ in expansion of an anisotropic non-linear sigma model. It is shown that at low resistance this system obeys a form of scaling which differs from the usual single-variable scaling hypothesis. The crossover between the regimes of zero and strong spin-orbit scattering is discussed. Weak localisation corrections to the electron spin relaxation rate are calculated and their possible experimental consequences are pointed out.