  We show that, in contrast to known results in the massive case, a minimally
gauged massless Rarita-Schwinger field yields a consistent classical theory,
with a generalized fermionic gauge invariance realized as a canonical
transformation. To simplify the algebra, we study a two-component left chiral
reduction of the massless theory. We formulate the classical theory in both
Lagrangian and Hamiltonian form for a general non-Abelian gauging, and analyze
the constraints and the Rarita-Schwinger gauge invariance of the action. An
explicit wave front calculation for Abelian gauge fields shows that wave-like
modes do not propagate with superluminal velocities. An analysis of
Rarita-Schwinger spinor scattering from gauge fields shows that adiabatic
decoupling fails in the limit of zero gauge field amplitude, invalidating
various "no-go" theorems based on "on-shell" methods that claim to show the
impossibility of gauging Rarita-Schwinger fields. Quantization of
Rarita-Schwinger fields, using many formulas from this paper, is taken up in
the following paper.
