As you might have heard, Donald Trump tweeted at a judge.

The commentariat shuddered at the effrontery of it, and some worried that the foundations of the separation of powers had been shaken. Trump’s slam of Judge James Robart was undeniably crude and ill-considered, but it wasn’t a threat to our republic.

In fact, it is a symptom of our distorted and overly sanctified view of the judiciary that a criticism of a judge with a lifetime appointment is greeted with such pearl-clutching. It is entirely appropriate that the political branches have their own view of the law and the Constitution and robustly contest — and even deny the legitimacy of — court decisions that they consider erroneous.

President Trump will have to go considerably further to come close to Andrew Jackson supposedly saying of a Supreme Court decision protecting the Cherokee Indians in Georgia, “John Marshall has made his decision; now let him enforce it.” Or to match the wars waged on uncongenial Supreme Court decisions by Franklin D. Roosevelt and Abraham Lincoln.

Trump is fully within his rights — indeed, it should be his responsibility — to defend the legal and constitutional prerogatives of the presidency as he sees them. Lincoln quoted Jackson for the proposition that “Each public officer, who takes an oath to support the Constitution, swears that he will support it as he understands it, and not as it is understood by others.”

Obviously, political actors can be self-interested in their evaluation of the work of the court. Because he couldn’t tweet, FDR gave fireside chats. In a notorious talk in 1937, he blasted the court for striking down New Deal legislation and proposed his court-packing scheme as the remedy (to get “new and younger blood” on the court, you understand).

If FDR’s court gambit is a blot on his record, Lincoln’s opposition to the Dred Scott decision redounds to his great credit. To say that Republicans weren’t deferential to the ruling is an understatement for the ages. They alleged a vast conspiracy of Chief Justice Roger Taney and top Democrats to commit offenses “comparable to the worst villainies of recorded history,” in the words of one historian.

Everyone would soon enough recognize Dred Scott as a disgrace. At the time, though, supporters of the decision considered it a means to peacefully settle a question tearing the country apart. For his part, Stephen Douglas made an argument that was simple and entirely familiar today: “Shut up, the Supreme Court justices have spoken.”

Lincoln allowed that Dred Scott applied to the particular parties to the case; he refused, though, to accept it “as a political rule.” This wasn’t Lincoln venting during an idle moment in his bathrobe. He devoted a portion of his first inaugural to developing his argument, and he governed as if the Dred Scott decision didn’t exist.

It’s an odd disconnect that Lincoln is justly considered perhaps the greatest statesman in American history, yet his rejection of judicial supremacy that was so central to his view of our system is roundly ignored.

It is certainly true that presidents defying the court willy-nilly would be a formula for chaos. But you see a Lincolnian political resistance to the court in, for instance, the pro-life movement that won’t rest until Roe v. Wade is overturned. The determined opposition to Citizens United is another example, from the left.

The fundamental point is that it is not just the executive or Congress that can abuse its power and overstep its bounds. The courts can, too, and no one is obligated to meekly accept their decisions.

Last week, a 9th Circuit panel upheld the temporary stay of Trump’s travel ban. If the courts in the end throw out the order, despite the black-and-white letter of the law giving him the authority to block aliens in the interest of national security, it will be a usurpatory act. In that scenario, the courts will have done more violence to our constitutional system than a foolish Trump tweet ever could.

Rich Lowry is a syndicated columnist. He can be reached via e-mail at: comments.lowry@nationalreview.com.