This is part of the Constitutinal doctrine referred to as "administrative due process".
Once you have completed "administrative due process" and have a letter in hand from an appropriate agency director that says "final agency decision" you can go to court.
There are other methods ~ go up the line to the guy's boss. Buy his boss a new car, maybe a boat.
There are a myriad of ways to handle this.
Usually the agency employees who make the decision are going to be found to be correct because, as it turns out, they work this stuff all the time and know what the winning answers are.
You can hire lawyers to handle this stuff for you ~ they specialize by agency.