What did Donald Trump do today?

He said he "didn't care" if a Democratic Congress subpoenaed his tax returns.

Trump's murky financial past, and the potential for corruption or criminality that goes with it, has been an issue since he first entered politics. Every presidential nominee since President Nixon has released his or her tax returns for public scrutiny, except for Trump. 

Recently, a New York Times report based on the Trump family business tax returns (also kept secret) shows that he almost certainly benefited from, and participated in, hundreds of millions of dollars in tax fraud over most of his adult life.

Asked today about the near-certainty that a Democratic House or Senate would subpoena his tax returns, Trump said, "I don't care. They can do whatever they want, and I can do whatever I want."

Under the rule of law, Trump cannot do "whatever" he wants when faced with a lawful subpoena, either as President or as a private citizen.

As for "I don't care," Trump still hasn't released his tax returns, in spite of occasionally promising that he would.

What is the problem with this?

• "I can do whatever I want" is pretty much the opposite of how the presidency works under the United States Constitution.

• At this point, it's hard to come up with an explanation for Trump's hiding of his tax returns that doesn't involve crimes.