  We examine the properties of a dc-biased quantum dot in the Coulomb blockade
regime. For voltages V large compared to the Kondo temperature T_K, the physics
is governed by the scales V and gamma, where gamma ~ V/ln^2(V/T_K) is the
non-equilibrium decoherence rate induced by the voltage-driven current. Based
on scaling arguments, self-consistent perturbation theory and perturbative
renormalization group, we argue that due to the large gamma, the system can be
described by renormalized perturbation theory for ln(V/T_K) >> 1. However, in
certain variants of the Kondo problem, two-channel Kondo physics is induced by
a large voltage V.
