In a supersymmetric model with the lightest supersymmetric particle (LSP) $��$ in the range of a few hundred MeV's, the decay $��{\longrightarrow} ������$ is going to be allowed. We investigate the departure from tau-universality caused by this decay. It is found that the universality violation in this way can be greater than both non-universal electroweak radiative corrections and supersymmetric one-loop corrections over a considerable region of the parameter space allowed by experiments so far. Thus it suggests a method of constraining the parameter space with light LSP's using data from tau-factories.

11 pages, LATEX, 3 figures (hard copies of figures available from the Authors on request)