Causal propagation of a charged spin 3/2 field in an external electromagnetic background

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 nonminimal couplings. No additional fields or equations besides the spin 3/2 ones are needed to solve the problem.