Perturbative Chern-Simons invariants from non-acyclic flat connections

We give a short review of our construction of a higher-loop perturbative invariant of framed 3-manifolds, generalizing the perturbative Chern-Simons invariant of Witten-Axelrod-Singer, associated to an acyclic flat connection, to an invariant given by the integral of a certain “Chern-Simons volume form” over a smooth closed component of the moduli space of flat connections.