>"There's no system that could prohibit you from looking up your ex-wife's new boyfriend, because your ex-wife's new boyfriend could come in contact with the criminal justice system,"
It is within the capability of current AI to be able to flag searches after the fact though. A particular officer does a lot more searches for people with no criminal background at all or other patterns that could be identified.
They should also have well thought out and implemented permission sets.
But, log everything is a good and simple place to start.