  It is deeply entrenched dogma that relativity theory prohibits superluminal
propagation. It is also experimentally well-established that under some
circumstances, classical electromagnetic fields propagate through a dielectric
medium with superluminal group velocities and superluminal phase velocities.
But it is usually claimed that these superluminal velocities do not violate the
relativistic prohibition. Here I analyze electromagnetic fields in a dielectric
medium within a framework for understanding superluminal propagation recently
developed by Geroch(1996, 2011) and elaborated by Earman(2014). I will argue
that for some parameter values, electromagnetic fields do propagate
superluminally in the Geroch-Earman sense.
