  Motivated by the severity of the bounds on Lorentz violation in the presence
of ordinary gravity, we study frameworks in which Lorentz violation does not
affect the spacetime geometry. We show that there are at least two inequivalent
classes of spontaneous Lorentz breaking that even in the presence of gravity
result in Minkowski space. The first one generically corresponds to the
condensation of tensor fields with tachyonic mass which in turn is related to
ghost-condensation. In the second class, realized by the DGP model or theories
of massive gravitons, spontaneous Lorentz breaking is induced by the
expectation value of sources. The generalization to de-Sitter space is also
discussed.
