  Explicit and spontaneous breaking of spacetime symmetry under
diffeomorphisms, local translations, and local Lorentz transformations due to
the presence of fixed background fields is examined in Einstein-Cartan theory.
In particular, the roles of torsion and violation of local translation
invariance are highlighted. The nature of the types of background fields that
can arise and how they cause spacetime symmetry breaking is discussed. With
explicit breaking, potential no-go results are known to exist, which if not
evaded lead to inconsistencies between the Bianchi identities, Noether
identities, and the equations of motion. These are examined in detail, and the
effects of nondynamical backgrounds and explicit breaking on the
energy-momentum tensor when torsion is present are discussed as well. Examples
illustrating various features of both explicit and spontaneous breaking of
local translations are presented and compared to the case of diffeomorphism
breaking.

General Relativity and Quantum Cosmology