Comment on 'Propagation and Negative Refraction,' IEEE Microwave   Magazine, pp. 58-65, July/August 2012
  We discuss and clarify some misleading statements appeared in a recent article on negative refraction in metamaterials. In this comment, we straighten the physical meaning and underlying phenomena behind negative refraction and negative index metamaterials and show that these phenomena are perfectly consistent with causality. It is hoped that this comment draws the attention of authors, reviewers and readers to the large body of rigorous analytical, numerical, and experimental evidence in favor of negative refraction at a single interface, so as to avoid reviving settled debates which mislead, rather than educate, the physics and engineering communities. 
George Eleftheriades, Andrea Alu
physics.optics cond-mat.mtrl-sci