Counterposition and negative refraction due to uniform motion
  Refraction of obliquely incident plane waves due to the interface of a vacuous half-space and a half-space occupied by a simply moving, nondissipative, isotropic dielectric-magnetic medium is considered, when the medium's velocity lies parallel to the interface and in the plane of incidence. Counterposition of the refracted wavevector and time-averaged Poynting vector occurs when the medium's velocity is sufficiently large in magnitude and makes an obtuse angle with the incident wavevector. The counterposition induced by relative motion occurs whether the refraction is negative or positive when the medium is at rest. 
Tom G. Mackay (University of Edinburgh), Akhlesh Lakhtakia   (Pennsylvania State University)