  We investigate the electromagnetic propagation in two-dimensional photonic
crystals, formed by parallel dielectric cylinders embedded a uniform medium.
The transmission of electromagnetic waves through prism structures are
calculated by the standard multiple scattering theory. The results demonstrate
that in certain frequency regimes and when the propagation inside the
scattering media is not considered, the transmission behavior mimics that
expected for a left-handed material. Such feature may illusively lead to the
conclusion that a left-handed material is fabricated and it obeys Snell's law
of negative refraction. We also discuss possible ambiguities that may be
involved in previous experimental evidence of left-handed materials.
