Until the judge starts putting IRS bureaucrats in jail for contempt, they will ignore him. So what he should do is what might be called “domino jailing”. Put the first one in jail then subpoena his *supervisor*, with a deadline to provide the information. His supervisor likely won’t cough it up either, so put him in jail and subpoena the supervisor’s supervisor.
Usually three levels will do it. Then the judge should subpoena several more first tier bureaucrats at once, and make them a deal: if just one of them provides the data, then they all walk. Only if they all refuse will they all go to jail.
Then, after a pause, let them all go. This will crack the dam. The next person subpoenaed will likely sing like a canary.
what do we have the Congress for? All we need is Judicial Watch.