  We present a Lagrangian for a massive, charged spin 3/2 field in a constant
external electromagnetic background, which correctly propagates only physical
degrees of freedom inside the light cone. The Velo-Zwanziger acausality and
other pathologies such as loss of hyperbolicity or the appearance of unphysical
degrees of freedom are avoided by a judicious choice of non-minimal couplings.
No additional fields or equations besides the spin 3/2 ones are needed to solve
the problem.
