  The simple Lorentz-nonreciprocal medium described by the constitutive
relations ${\bf D}=\epsilon_o\epsilon_r{\bf E]-{\bf\Gamma}\times{\bf H}$ and
${\bf B}=\mu_o\mu_r{\bf H]-{\bf\Gamma}\times{\bf E}$ is inspired by a specific
spacetime metric, $\bf\Gamma$ being the magnetoelectric-gyrotopy vector. Field
representations in this medium can be obtained from those for the isotropic
dielectric-magnetic medium. When a plane wave is incident on a half space
occupied by the Lorentz-nonreciprocal medium with magnetoelectric gyrotopy,
theory shows that the transverse component of the magnetoelectric-gyrotopy
vector is responsible for a rotation about the normal axis; furthermore,
left/right reflection asymmetry is exhibited. Additionally, left/right
transmission asymmetry is exhibited by a planar slab composed of the
Lorentz-nonreciprocal medium with magnetoelectric gyrotopy. The left/right
asymmetries are of interest for one-way devices.
