When they battle for public opinion, Republicans tend to operate on the principle that no argument is too stupid to make. Global warming is a hoax, cutting taxes for the wealthy helps regular folks, President Trump is extremely concerned with corruption — if you get enough people to repeat your ludicrous claim, it will be treated as serious and worthy of consideration.

When you get into court, however, it becomes quite a bit harder to serve up laughable claims. This is what Trump and his advocates are discovering as they desperately try to shield his tax returns from public view.

They just suffered another defeat in that long battle: A three-judge panel of the Court of Appeals for the D.C. Circuit has ruled against Trump in his lawsuit to keep Congress from seeing his tax returns.

When Trump first decided to refuse to release his returns, he promised to release them as soon as he was done being audited by the IRS, which turned out to be a lie. When he became president, his spokespeople said that the election is over and he won, so stuff it.

But things changed when Democrats won the House. Now they have both subpoena power and the right to demand that the IRS turn over any American’s tax returns. Trump’s cronies and hacks resisted the latter demand, but Democrats on the House Oversight Committee did something clever: Instead of subpoenaing Trump, they subpoenaed Mazars, his accounting firm, a company that is presumably reluctant to simply ignore the law.

Trump sued to block Mazars from releasing Trump’s financials. Despite a long history of courts ruling that Congress has broad oversight powers, Trump asserted that the committee’s subpoenas to his accounting firm are unlawful because they’re politically motivated and Congress doesn’t have a good enough reason for asking.

That’s despite the fact that the committee cited its oversight of ethics rules and the possibility that new legislation might be needed to update them. That’s a pretty clear and persuasive argument, since the Trump presidency demonstrates that our current ethics rules are inadequate when confronted with a president as spectacularly corrupt as Trump.

The Oversight Committee also specifically noted the testimony of former Trump lawyer and current federal inmate Michael Cohen, who alleged that Trump lied about his income and assets to banks in order to obtain loans, which if proven would constitute bank fraud.

So a 2-1 majority of the appeals court panel affirmed the lower court decision that Trump lost and ruled that the subpoena is indeed within Congress’s powers to issue. So pending the inevitable appeal, Mazars will have to turn over eight years of Trump’s tax returns.

But Trump might still be taking solace from a dissent, written by Judge Neomi Rao, a newcomer on the appeals court who was recently appointed by Trump. She took the rather extraordinary position that “allegations of illegal conduct against the President cannot be investigated by Congress except through impeachment,” and since the Oversight Committee is not impeaching Trump, they can’t demand his tax records from his accounting firm, no matter what their legislative purpose.

Despite the loss, it’s possible that Trump views Rao’s dissent as a hint of how the courts might side with him later. If he appealed to the full circuit court — which has a majority of judges appointed by Republican presidents — might they accept that argument, no matter how inane and utterly unsupported by precedent it is? And since this case will almost certainly wind up before the Supreme Court in a matter of months, will five justices bail Trump out?

Trump’s problem is he’s facing a crush of cases involving his tax returns, all at the same time. He just lost at the district court level in another case involving an investigation by the New York district attorney. The judge in that case called Trump’s assertion that the president can’t even be investigated for wrongdoing “repugnant to the nation’s fundamental structure and constitutional values.”

There are three separate cases hurtling up the ladder: the Oversight Committee case, the New York D.A. case and the case filed by the Ways and Means Committee. If Trump loses any of the three, his tax returns will likely become public in short order. Everyone, Republicans and Democrats alike, agrees that what the returns reveal will be scandalous. Tax avoidance? Definitely. Tax evasion? Probably. Partnerships with shady characters, even criminals? No one will be surprised.

And if it happens, it will be in the heart of the 2020 presidential campaign.

Trump did get one piece of good news today: Deutsche Bank, long the only bank reckless enough to lend him money, told a court in another case that it is not actually in possession of Trump’s tax returns, so Congress can’t get the returns from them.

But with the other three cases in the pipeline, there’s only one group of people that can save Trump: John G. Roberts Jr., Clarence Thomas, Samuel Alito, Neil M. Gorsuch, and Brett M. Kavanaugh.

These cases will end up before the Supreme Court, and all five conservative justices will have to agree that no matter what the Constitution and the law say, what matters is protecting Trump. I wish I could say there’s no way they will.

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