But to anyone who lived through the Merrick Garland and Brett Kavanaugh nominations, the idea that this norm would be resilient absent Trump’s Twitter provocations seems laughable. What was once a conservative assumption dismissed as extremism by the bien-pensants — that the Supreme Court is a highly ideological institution defined by partisan bias and anti-democratic overreach — is now a commonplace liberal belief as well. And when non-Trump politicians hail about the court’s independence, it’s usually just an exercise in tribalism with no consistency behind it.

In this sense the really telling tweet last week came from Chuck Schumer, the Senate minority leader, who weighed in with the following praise — or “praise,” perhaps — for the chief justice:

“I don’t agree very often with Chief Justice Roberts, especially his partisan decisions which seem highly political on Citizens United, Janus, and Shelby. But I am thankful today that he — almost alone among Republicans — stood up to President Trump and for an independent judiciary.”

Read these sentences over a few times, and relish their internal contradictions. John Roberts is to be commended for standing up for an “independent judiciary,” Schumer suggests, so long as he is attacking President Trump. But when he is issuing rulings with which Schumer disagrees, he is a “partisan” and “highly political” and a “Republican.”

Save for the pious tone there is little practical difference between this intervention and Trump’s rants about “Obama judges.” Which in turn suggests that in the case of Trump v. Roberts, our president is mostly just exposing a degradation that already exists, acknowledging a truth of our constitutional order that’s badly disguised by official-D.C. politesse.

That truth reflects an old problem joined to several new ones. The old problem is that the Supreme Court’s legal supremacy over the White House depends upon the presidency’s willingness to accept the court’s rulings. From Andrew Jackson’s conflict with John Marshall over Cherokee removal to Abraham Lincoln’s suspension of habeas corpus to Franklin Roosevelt’s attempts to force the court to accept the New Deal, there have always been tensions in the American republic between judicial authority and presidential power.