  Torsion propagation and torsion-spin coupling are studied in the perspective
of the Velo-Zwanziger method of analysis; specifically, we write the most
extensive dynamics of the torsion tensor and the most exhaustive coupling that
is permitted between torsion and spinors, and check the compatibility with
constraints and hyperbolicity and causality of field equations: we find that
some components of torsion and many terms of the torsion-spin interaction will
be restricted away and as a consequence we will present the most general theory
that is compatible with all restrictions.
