  A systematic expansion in opacity, $L/\lambda$, is used to clarify the
non-linear behavior of induced gluon radiation in quark-gluon plasmas. The
inclusive differential gluon distribution is calculated up to second order in
opacity and compared to the zeroth order (factorization) limit. The opacity
expansion makes it possible to take finite kinematic constraints into account
that suppress jet quenching in nuclear collisions below RHIC ($\sqrt{s}=200$
AGeV) energies.
