Many, perhaps most fantasy lands are monarchies, which can be ruled well when the monarch is a clever and able man or woman devoted to his or her people. But what happens when the monarch is ill, or is tyrannically cruel, or a young child, or is otherwise blatantly unfit to rule? How can he or she be dealt with without risking civil war as powerful nobles fight for the crown?
A lot of what adventurers do is illegal, from fighting and carrying weapons in towns, to robbery and tomb raiding. Sooner or later, many of them are going to be arrested and find themselves up before a judge.
In the Cosmic Era, the proliferation of arcanotech, cyborgs, robots, parapsychic threats, black market weapons, new illegal drugs constantly hitting the market, all backed up by large organized criminal syndicates, the average police officer doesn't stand a chance.