  We propose the second-order response of metals in an electric field induced
by magnetic impurities which locally break inversion symmetry. The impurities
with toroidal moments scatter conduction electrons in the presence of the
spin-orbit coupling, leading to nonreciprocal response. This mechanism is
ubiquitous when a magnetic impurity is placed off an inversion center such as
an interstitial site and a surface of a two-dimensional system.
