[en] The I (V) characteristic of a superconductor-insulator-superconductor tunneling junction in which both of the superconductors are driven out of equilibrium is investigated. We show that the steady-state quasiparticle distribution function is related to the I (V) characteristic by a linear integral equation. Modifications of the I (V) characteristic due to nonequilibrium distributions produced by phonon and microwave irradiation are discussed