Official Positions

When a fantasy country has an official archmage, lord high wizard, conjurer supreme, archon thaumaturge, etc., what are the chances he's actually good at it, and what are the chances he's the best? That's what you have to consider. The default is probably that his skills are decent but not extraordinary whereas his ancestors were extraordinary but far from decent.

Addendum

Relatively speaking, of course. An empire can't be counted upon for reliable law enforcement across all its possessions, territories, client kingdoms, and so forth. What you really want is a mage judge.

Surely Somebody's Done This Already

Fairy Mason

The Next Crossover

Perry Mason vs. Perry Rhodan. By vs. of course I mean they have to team up to defeat the bad guy at the end, who is probably some sort of space district attorney. On a gigantic spaceship that serves as a circuit court. What a district attorney is doing on a circuit court ship is something for the eventual author to figure out.