  We discuss the DC conductivity of holographic theories with translational
invariance broken by a background lattice. We show that the presence of the
lattice induces an effective mass for the graviton via a gravitational version
of the Higgs mechanism. This allows us to obtain, at leading order in the
lattice strength, an analytic expression for the DC conductivity in terms of
the size of the lattice at the horizon. In locally critical theories this leads
to a power law resistivity that is in agreement with an earlier field theory
analysis of Hartnoll and Hofman.
