  We study a two-dimensional electron system in the presence of spin-orbit
interaction. It is shown analytically that the spin-orbit interaction acts as a
transversal effective electric field, whose orientation depends on the sign of
the $\hat{z}$-axis spin projection. This effect doesn't require any driving
external field and is inherent to the spin-orbit interactions present in
semiconductor materials. Therefore, it should manifest in both closed and open
systems. It is proposed an experiment to observe the intrinsic spin Hall effect
in the far infrared absorption of an asymmetric semiconductor nanostructure.
