  Lagrangian of a massive particle with spin 3/2 is considered in the
Rarita-Schwinger formalism. We discuss implications of the contact- and the
gauge-transformation on the physical content of free and interacting theories.
It is shown that the ``contact-invariance'' is trivial and has no physical
relevance. The requirement of the gauge-invariance of the free lagrangian fixes
the off-shell lower-spin content of the spin-3/2 field. The gauge-invariance of
the interaction lagrangian insures that these lower-spin components are not
coupled, and (probably always) leads to theories consistent with local
causality.
