  We study the dynamical response to small distortions of a lattice about its
uniform state, drifting through a dissipative medium due to an external force,
and show, analytically and numerically, that the fluctuations, both transverse
and longitudinal to the direction of the drift, exhibit spatiotemporal scaling
belonging to the Kardar-Parisi-Zhang universality class. Further, we predict
that a colloidal crystal drifting in a constant electric field is linearly
stable against distortions and the distortions propagate as underdamped waves.
