  By definition a spacetime is stably causal if it is possible to widen the
light cones all over the spacetime without spoiling causality. We prove that if
the spacetime is at least non-total imprisoning then it is stably causal
provided the light cones can be widened outside any compact arbitrarily large
set, i.e. in a neighborhood of infinity, without spoiling causality.
Furthermore, we prove that the new causality level `compact stable causality'
can be obtained as the antisymmetry condition of a new causal relation which we
identify, but it cannot be obtained as a causal stability condition with
respect to a topology on metrics. The difference between stable causality and
compact stable causality is shown to follow from the fact that Geroch's
interval topology on the space of conformal metrics of M is not Frechet-Urysohn
(in fact it is not even T-sequential). In particular we prove that (compact)
stably causal metrics are those in the (sequential) interior of the set of
chronological metrics. Finally, contrary to previous claims it is shown that
stable causality with respect to the C^0 fine topology on metrics leads to the
usual notion of stable causality.
