 A deterministic theory must satisfy the condition of outcome independence, and hence if one accepts \((a)\) that a violation of PI, that is, a situation in which the choice of an experiment on one side changes the probability of an outcome on the other, is an instance of causation, and \((b)\) that a cause must temporally precede its effect, and then it follows that a deterministic theory that satisfies the supplementary conditions and reproduces the quantum correlations is incompatible with relativistic spacetime structure. Such a theory may, however, be Lorentz invariant at the phenomenal level, if (as in the de Broglie-Bohm theory) the distinguished foliation is unobservable.