  We present a new parametrization of the minimal seesaw model, expressing the
heavy-singlet neutrino Dirac Yukawa couplings $(Y_\nu)_{ij}$ and Majorana
masses $M_{N_i}$ in terms of effective light-neutrino observables and an
auxiliary Hermitian matrix $H.$ In the minimal supersymmetric version of the
seesaw model, the latter can be related directly to other low-energy
observables, including processes that violate charged lepton flavour and CP.
This parametrization enables one to respect the stringent constraints on
muon-number violation while studying the possible ranges for other observables
by scanning over the allowed parameter space of the model. Conversely, if any
of the lepton-flavour-violating process is observed, this measurement can be
used directly to constrain $(Y_\nu)_{ij}$ and $M_{N_i}.$ As applications, we
study flavour-violating $\tau$ decays and the electric dipole moments of
leptons in the minimal supersymmetric seesaw model.
