  We demonstrate that the fluctuation theorem of Gallavotti and Cohen can be
used to characterize the class of dynamics that arises in nonthermal systems of
collectively interacting particles driven over random quenched disorder. By
observing the frequency of entropy-destroying trajectories, we show that there
are specific dynamical regimes near depinning in which this theorem holds.
Hence the fluctuation theorem can be used to characterize a significantly wider
class of nonequilibrium systems than previously considered. We discuss how the
fluctuation theorem could be tested in specific systems where noisy dynamics
appear at the transition from a pinned to a moving phase such as in vortices in
type-II superconductors, magnetic domain walls, and dislocation dynamics.
