The steady-state space-charge-limited current at high electric fields in an insulator or high-resistance semiconductor with traps is analyzed theoretically. Poole-Frenkel carrier emission from traps is considered. The analysis ofthe space-charge centroid yields a current -voltage characteristic in analytical form. These results are compared with experimental data on the conductivity of Si,N, films. The obtained characteristic gives a good fit to the observed relation between the current and the film thickness. The trap density in Si,N, is determined to be (5 to 8)x 10" cm-,.