  In this paper, we consider a theory defined by an energy-momentum tensor
depending on a set of general fields, including the space-time metric. We prove
that if the theory is causal, bounded and transforms appropriately under
diffeomorphism, it will depend only on the local values of the independent
fields and their covariant derivatives up to a finite order. The implications
are that the energy-momentum tensor of a causal relativistic fluid can only
depend on covariant derivatives only up to a finite order.
