  The gauging of the lepton flavour group is considered in the Standard Model
context and in its extension with three right-handed neutrinos. The anomaly
cancellation conditions lead to a Seesaw mechanism as underlying dynamics for
all leptons; requiring in addition a phenomenologically viable setup leads to
Majorana masses for the neutral sector: the type I Seesaw Lagrangian in the
Standard Model case and the inverse Seesaw in the extended model. Within the
minimal extension of the scalar sector, the Yukawa couplings are promoted to
scalar fields in the bifundamental of the flavour group. The resulting
low-energy Yukawa couplings are proportional to inverse powers of the vacuum
expectation values of those scalars; the protection against flavour changing
neutral currents differs from that of Minimal Flavor Violation. In all cases,
the $\mu-\tau$ flavour sector exhibits rich and promising phenomenological
signals.
