  It is shown that magnetic forces as the Lorentz force, exerted on electric
currents, and the force {\mu}Div(B), exerted on electron spins at rest, account
for both the transverse spin imbalance typical of spin Hall effect and the
transverse charge imbalance associated with pure spin currents (inverse spin
Hall effect). Considering that for stationary currents the laboratory reference
frame and those for which the spin up and spin down carriers are at rest are
inertial systems, one can easily find the forces exerted by the lattice on both
spin sub-bands, as well as the force between sub-bands.
