  In the most general R-parity violating model, including both bilinear and
trilinear terms, the sneutrino receives a vacuum expectation value. We
investigate the constraints on this vev following a basis independent approach,
highlighting the relations between the three most popular basis. We study the
prediction for the tau neutrino mass which follows from the minimization of the
scalar potential in a SUGRA model with universality of the soft parameters at
the GUT scale. Finally we show that the tau neutrino mass controls the R-parity
violating effects both in the fermionic and scalar sectors.
