  Out of conviction or expediency, some current research programs take for
granted that "PCT violation implies violation of Lorentz invariance". We point
out that this claim is still on somewhat shaky ground. In fact, for many years
there has been no strengthening of the evidence in this direction. However,
using causal perturbation theory, we prove here that when starting with a local
PCT-invariant interaction, PCT symmetry can be maintained in the process of
renormalization.
