David French explains at National Review Online why he believes the president will lose his latest legal battle.

I believe three things at the same time. First, Donald Trump should have voluntarily produced his tax returns years ago. Second, the law Democrats are using to demand production of Trump’s returns — which grants the chairman of the House Ways and Means Committee the right to see the returns of any American taxpayer — is overbroad and vulnerable to abuse. And third, the lawsuit Trump has just filed in hopes of repelling that demand is both frivolous and (to the extent the courts pay it any mind) dangerous to our constitutional system of checks and balances.

The core problem with Trump’s lawsuit is clear: It defies Congress’s inherent investigative authority by defining Congress’s “legislative sphere” so narrowly that it would prohibit Congress from meaningfully investigating the president. Moreover, it argues, “‘Oversight’ and ‘transparency,’ in a vacuum, are not legitimate legislative purposes that can justify subpoenaing a private citizen.”

But wait. Didn’t we just finish a multi-year national ordeal during which Donald Trump’s defenders consistently argued that investigation of the executive branch was a legislative function — i.e. that it was ridiculous for the executive branch to “investigate itself,” and it was ridiculous for anyone to believe that the president could obstruct justice if he tried to impede or supervise that probe, because the investigators worked for him?

Yes, yes we did. So it strains credulity for those same folks, when Congress launches such an investigation — empowered, in this case, by a specific statute that grants it the ability to see Trump’s returns and by an enormous reservoir of inherent authority through its lawmaking and impeachment powers — to turn around and argue that it’s acting as “law enforcement,” and law enforcement is exclusively the president’s responsibility.