Here is the backstory.

During the last year of his first term in office, Trump's tax returns were stolen along with those of 425,000 others by an IRS employee who leaked Trump's to media outlets. The acts of stealing and leaking were, of course, criminal, and the now-former IRS employee who pleaded guilty to theft of government documents served nearly four years in federal prison. 

But the publication of the returns was protected under the Supreme Court's Pentagon Papers case. In that case, Daniel Ellsberg famously stole documents from the Department of Defense, where he was a civilian employee.

When word got out that he had delivered about 7,000 pages to The New York Times and The Washington Post, the Nixon Department of Justice filed complaints in two federal courts and obtained restraints on both newspapers preventing publication. The stolen documents revealed that American generals had been misleading President Lyndon B. Johnson about success in the Vietnam War, and LBJ had been misleading the public.

The Supreme Court bypassed two intermediate appellate courts and accepted appeals directly from the trial courts' decisions that imposed the injunctions.

After a very short briefing schedule and a memorable oral argument, the court ruled that while the thief who stole the secrets can be prosecuted, media outlets that publish even stolen matters that are material to the public interest may do so without criminal prosecution or civil liability. This was the high-water mark for press freedom in America.

When various publications and websites published Trump's tax returns, his lawyers persuaded him that the Pentagon Papers case was so well-settled that he shouldn't bother suing anyone in the media; and the thief, by then sitting in a federal prison, was effectively judgment-proof.

So, Trump waited until after he returned to the White House to sue the IRS for permitting the theft. Surely, a private citizen who has been harmed by grossly negligent government behavior should have a cause of action against the government. 

But how about the president suing the IRS, which works for him? And how can the IRS be represented by the Department of Justice, which also works for the president? And how can the Acting Attorney General, who is Trump's former criminal defense lawyer, permit the DoJ he supervises to be adverse to the president, who is the chief federal law enforcement officer in the land?