  A model of reality is called separable if the state of a composite system is
equal to the union of the states of its parts, located in different regions of
space. Spekkens has argued that it is trivial to reproduce the predictions of
quantum mechanics using a separable ontological model, provided one allows for
arbitrary violations of `dynamical locality'. However, since dynamical locality
is strictly weaker than local causality, this leaves open the question of
whether an ontological model for quantum mechanics can be both separable and
dynamically local. We answer this question in the affirmative, using an
ontological model based on previous work by Deutsch and Hayden. Although the
original formulation of the model avoids Bell's theorem by denying that
measurements result in single, definite outcomes, we show that the model can
alternatively be cast in the framework of ontological models, where Bell's
theorem does apply. We find that the resulting model violates local causality,
but satisfies both separability and dynamical locality, making it a candidate
for the `most local' ontological model of quantum mechanics.
