  The pure lepton decay of the polarized muon is considered, accounting for a
new tensor interaction which is outside of the Michel local interactions. This
interaction leads to new energy distribution and polarization of the final
charged lepton. The presence of such a type of interaction is strongly required
for the description of the latest experimental results on the weak radiative
pion decay in the full kinematic region. Assuming quark--lepton universality,
predictions for a deviation from the Standard Model are made using only one new
parameter. They do not contradict the present experimental data and can be
verified further in the on-going experiments at PSI and TRIUMF, at least to the
level of 3 standard deviations.
