  We employ path integral methods to calculate the Casimir energy and force
densities in a chiral extension of QED. Manifestly gauge invariant perfect
electromagnetic boundary conditions, a natural generalization of perfect
electric and perfect magnetic conditions, are implemented directly in the
action by the usage of auxiliary fields. The chiral properties of the vacuum
are modelled using a background $\theta$ field, and we introduce techniques to
efficiently calculate the path integral in this chiral medium. The flexibility
of our method allows us to naturally obtain results for a variety of
configurations, and where comparison is possible our results are in perfect
agreement with existing literature. Among these are multiple situations where a
repulsive Casimir force is possible.
