What is the weak charge of the electron?

The experimental results on nu /sub mu /-electron scattering, when interpreted within SU/sub 2/*U/sub 1/ theories put severe constraints on the weak charge of the right-handed electron. Under very general assumptions it is shown that the cases I/sub 3//sup weak/(e/sub R//sup -/)=0 or -/sup 1///sub 2/ are possible. The case I/sub 3//sup weak/(e /sub R//sup -/)=+/sup 1///sub 2/ is found to be unlikely. All other assignments for e/sub R//sup -/ are excluded. Consequences for parity violation in atomic physics are discussed. (12 refs).