We have compared the charge created inp‐metal–oxide–semiconductor capacitors by Fowler–Nordheim injection from the gate and from the substrate. We have shown that an injection from the gate creates a negative charge, trapped holes, and positively charged slow states whereas an injection from the substrate creates a negative charge, slow states, and amphoteric neutral traps; once charged these neutral traps are discharged irreversibly, as are the trapped holes, by an appropriate gate bias. We have observed that the discharge of the trapped holes, and the charge or discharge of the slow states, obey the same general law, but the time response of the trapped holes is always shorter than the time response of the slow states. This general law is equivalent to the so‐called ‘‘universal law,’’ which is the law which describes the time dependence of current observed in any dielectric in response to a step‐function field. ©1996 American Institute of Physics.