  In multi-Higgs-doublet models, requiring simultaneously that (i) CP violation
only arises spontaneously, (ii) tree level scalar flavour changing couplings
are absent and (iii) the fermion mixing matrix is CP violating, can only be
achieved in a very specific manner. A general approach with new clarifying
insights on the question is presented. Considering the quark sector, that
peculiar possibility is not viable on phenomenological grounds. We show that,
considering the lepton sector, it is highly interesting and leads to viable
models with $\mu-\tau$ symmetric PMNS matrices. Phenomenological implications
of the models, both for Dirac and Majorana (in a type I seesaw scenario)
neutrinos, are analysed.
