Probing Lorentz violation with Doppler-shift experiments

We analyze Doppler-effect experiments in terms of a general framework for violations of Lorentz symmetry: the Standard-Model Extension. These experiments are found to be sensitive to heretofore unprobed combinations of Lorentz-violation coefficients associated with protons and electrons. New bounds at the level of ${10}^{-11}$ and ${10}^{-8}$ for proton coefficients and ${10}^{-2}$ for electron coefficients emerge from a recent experiment.