  Even for holographic theories that obey boundary causality, the full bulk
Lorentzian path integral includes metrics that violate this condition. This
leads to the following puzzle: The commutator of two field theory operators at
spacelike-separated points on the boundary must vanish. However, if these
points are causally related in a bulk metric, then the bulk calculation of the
commutator will be nonzero. It would appear that the integral over all metrics
of this commutator must vanish exactly for holography to hold. This is puzzling
since it must also be true if the commutator is multiplied by any other
operator. Upon a careful treatment of boundary conditions in holography, we
show how the bulk path integral leads to a natural resolution of this puzzle.
