He was in jail at the time and the summons was improperly served.
The court has no right to use a summons that couldn’t be served and it should vacate the entire judgment.
Due process was not followed. Sorry if that costs the state $30,000.
Which in any case is the fruit of the poisonous tree.
You’re close. He needs to argue that the judgment is void because the state did not get good service on him. Without good service, the court that entered the judgment didn’t have jurisdiction over him and the judgment is therefore a nullity.
It’s usually hard to contest service this long after the fact, but here he can prove he was incarcerated at the time of service and could not have been the person the process server encountered.