  A quantum phase space version of the continuity equation for systems with
internal degrees of freedom is derived. The $1$ -- D Dirac equation is
introduced and its phase space counterpart is found.
  The phase space representation of free motion and of scattering in a
nonrelativistic and relativistic case for setups with internal degrees of
freedom is discussed and illustrated.
  Properties of Wigner functions of unbound states are analysed.
