The spin-extended semiclassical chiral fermion (we call the S-model), which
had been used to derive the twisted Lorentz symmetry of the "spin-enslaved"
chiral fermion (we call the c-model) is equivalent to the latter in the free
case, however coupling to an external electromagnetic field yields
nonequivalent systems. The difference is highlighted by the inconsistency of
spin enslavement within the spin-extended framework. The S-model exhibits
nevertheless similar though slightly different anomalous properties as the
usual c-model does. The natural Poincar\'e symmetry of the free model remains
unbroken if the Pfaffian invariant vanishes, i.e., when the electric and
magnetic fields are orthogonal, ${\bf E}\cdot{\bf B}=0$, as in the Hall effect.Comment: Revised and extended version= 14 pages, 1 figure. The framework
better explained. Some details clarified and a section on Poincare symmetry
adde