On all fronts, Trump, through his lawyers, is fighting congressional subpoenas issued to him, his businesses, his sons, etc. in the courts.
Trump and his allies are working to block more than 20 separate investigations into his actions as president, his personal finances and his administration’s policies, according to a Washington Post analysis.

The most important case of all is, ironically, one that Trump brought seeking to block Congress from obtaining his financial records from the accounting firm Mazars USA. Trump’s lawyers actually asserted that Congress has no oversight role in examining corruption, conflicts of interest or any other matter. The Justice Department can do it, they argue (!). All Congress can do is pass bills.

U.S. District Judge Amit P. Mehta seemed stunned. The Post reports:

“Is it your position that whether the president has properly reported his finances [under federal disclosure laws], that’s not subject to investigation by Congress?” Mehta asked.

“Say a president was involved in some corrupt enterprise — you mean to tell me because he is the president of the United States, Congress would not have power to investigate?” Mehta asked, saying that what if “we’re talking about a presidential violation of a constitutional prohibition that only Congress has authority to approve,” such as the acceptance for emoluments or gifts from a foreign government.

[William S.] Consovoy answered yes, saying that determining whether a president properly disclosed his finances was a “pure law enforcement function,” not a matter for Congress, whose fundamental duty, he said, is writing bills.

And if Congress did seek to enact legislation, whether to tighten ethics requirements, fight public corruption or enforce a constitutional prohibition on acceptance of foreign emoluments, Consovoy said, “I don’t think there is any permutation of any of these proposals that could pass constitutional muster,” because they would interfere with the president’s execution of his duties, or add qualifications for his office.

You see, according to Trump’s lawyers, nothing — certainly not Congress — can “interfere” with the president.

But that’s precisely what the Framers rejected in drafting the Constitution. Interference is nothing more than checks and balances.

“Consovoy’s arguments on behalf of Trump, seeking to block private entities from turning over documents and information needed by Congress to perform its Article I functions, are so preposterous that Judge Mehta had no choice but to resist them,” says constitutional scholar Laurence Tribe. “For the district court to accept those arguments would be astonishing — an unthinkable loss for the separation of powers. For the district court to reject those Trump arguments, as I expect it to do, will be an unsurprising win — a big victory but too predictable to count as a game-changer.”

By making an argument that virtually writes Congress out of the equation, Trump’s lawyers may have set him up for a rude awakening on the subject of separation of powers. As Tribe put it, “It’ll be a self-inflicted wound suffered by Team Trump.”

Ominously for Trump and his stonewalling lackeys, Mehta observed, “There’s not a single Supreme Court or appellate case since 1880 that has found Congress overstepped its legislative authority by issuing a subpoena.” Oops.

In fact, the legal argument is so absurd that it is not hard to imagine that there is another strategy being employed: delay. Delay for what? Possibly the hope that nothing comes to light during the 2020 election. But the delay itself could become an election issue.

It is hard to see this playing out in Trump’s favor.