In the past, presidents have gone to almost any length to assure the public that there wouldn't be even the barest suggestion of impropriety regarding their personal finances. Jimmy Carter put his peanut farm in a trusteeship. Barack Obama refused to refinance his mortgage when rates fell, saying that "When you're president you have to be a little careful about these transactions."

President Donald Trump would no doubt say that they were suckers. Not only has he continued to seek every opportunity he can to make money while president, but also he has essentially declared that where he gets his money from and what he does with it are nobody's business. The obvious reason − the voluminous evidence that he is spectacularly corrupt, in some ways that are simply appalling and in others that bear directly on the presidency − is precisely why it's so important that we see what he's hiding.

So far, Trump has been successful in erecting walls of concealment around his finances. But those walls are beginning to crack.

Look at what happened to Trump just last week:

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[naviga:li]On Wednesday, a federal judge in New York rejected Trump's attempt to block Deutsche Bank and Capital One from complying with a congressional subpoena for records relating to his dealings with the banks, and Deutsche Bank said that it would abide by the court order and supply the requested documents. Deutsche Bank might be the real mother lode here, since for years it was the only major bank that would lend to Trump, under circumstances that appear shady at best.[/naviga:li]

[naviga:li]NBC reports that Wells Fargo and TD Bank have already turned over records to the House Financial Services Committee regarding their dealings with Trump.[/naviga:li]

[naviga:li]The New York state legislature passed a bill to turn over Trump's state tax returns to congressional committees upon request.[/naviga:li]

[naviga:li]A week ago, another federal judge rejected Trump's suit attempting to block his accounting firm, Mazars USA, from complying with a congressional subpoena for his financial records.[/naviga:li]

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In both the federal cases, Trump's attorneys attempted to argue that Congress has no right to demand these kinds of records or even investigate the president at all, claims the judges found almost laughable. "The court concludes that the plaintiffs have not raised any serious questions," the judge in one case wrote. "It is simply not fathomable," the judge in the other case said, "that a Constitution that grants Congress the power to remove a President for reasons including criminal behavior would deny Congress the power to investigate him for unlawful conduct − past or present."

The legal problem Trump and his attorneys face is that there is a long line of jurisprudence establishing that Congress' oversight powers are extremely broad. And one must acknowledge their spectacular chutzpah, to claim that Congress has no legitimate reason to investigate the finances of a president with a long history of not only scams and cons such as Trump University but also a series of sketchy overseas business deals that have the potential to influence the way he conducts foreign policy.

That's not to mention the fact that he was trying to negotiate a deal to build a project in Moscow while running for president and proposing more Kremlin-friendly policies (and denying he had any business interests there). If there was ever a president who demonstrated the danger of having his financial interests affect the national interest, it's this one.

But if there's about to be an avalanche of Trump financial documents heading to Congress and ultimately to the public, we should understand that it's going to take some time to sort out. Trump has lots of experience in making his business dealings as convoluted and opaque as possible, in large part to avoid paying taxes; you'll recall the New York Times investigation last year that revealed that in the 1980s and 1990s he and his family engaged in a massive tax fraud scheme worth hundreds of millions of dollars, one that involved the creation of shell companies and other means of obscuring the fraud.

And the Trump Organization itself is actually made up of approximately 500 separate entities and partnerships, most of which probably have vague-sounding names that make it difficult to understand what they do without some digging. So unraveling it all to find out what was legitimate, lawful, ethical and presented no conflict of interest with Trump's job as president − and what wasn't − is an enormous task.  

But that task is an absolutely critical one.

Paul Waldman is an opinion writer for the Plum Line blog.