A CMOS chip input generally includes both P channel and N channel transistors. If the chip is powered, then the (tiny) gate leakage currents can be in either (or both) directions: to ground, or to some internal voltage rail(s). The process variation may not allow one to pre-determine which direction of leakage is greater.

A CMOS chip's input circuit generally includes both P channel and N channel transistors. If the chip is powered, then the (tiny) gate leakage currents can be in either (or both) directions: to ground, or to some internal voltage rail(s). The process variation may not allow one to pre-determine which direction of leakage is greater (unless the chip was designed with specific direction and process+operating margin).