Bad Watchdog Season 2 launches June 20.

—“I’ve been treated very unfairly by this judge. Now, this judge is of Mexican heritage. I'm building a wall, OK? I'm building a wall… I think he should recuse himself” (June 3, 2016)

—“The opinion of this so-called judge, which essentially takes law-enforcement away from our country, is ridiculous and will be overturned!” (February 4, 2017)

—“Just cannot believe a judge would put our country in such peril. If something happens blame him and court system. People pouring in. Bad!” (February 5, 2017)

—“It just shows everyone how broken and unfair our Court System is when the opposing side in a case (such as DACA) always runs to the 9th Circuit and almost always wins before being reversed by higher courts.” (January 10, 2018)

Judges are no strangers to criticism. It is perfectly appropriate, and in fact healthy, for the public and politicians to speak out when a judge decides a controversial case or makes a mistake. Presidential administrations have lost court cases since the earliest days of the Constitution and have often forcefully responded to being on the losing end of a decision.

But in the modern era, there have been strong norms regarding how presidents frame a perceived “setback” from the courts. While they may criticize the ruling, they avoid casting doubt on the basic legitimacy of the courts. And with good reason: rhetoric that undermines the very lawfulness of the courts can make it easier for the executive branch to defy judicial rulings, giving rise to a full-blown constitutional crisis. The public’s lack of faith in the courts can also lay the groundwork for Congressional efforts to limit the courts’ jurisdiction and, consequently, its ability to protect both the structural guarantees and individual rights and liberties found in the Constitution. For the system to work, it’s essential that everyone respect the outcome—even if they don’t like it.

So, the question is: are President Trump’s attacks on the judiciary part of the rough and tumble of politics, or do they cross a dangerous line?

It’s valuable to consider how presidents typically handle conflict with the courts. George W. Bush’s response to the Supreme Court’s 2008 ruling in Boumediene v. Bush, where the Court ruled that “enemy combatants” held at Guantanamo Bay have a right to habeas corpus to challenge their detention, exemplifies this norm: “We’ll abide by the court’s decision—that doesn’t mean I have to agree with it.”

President Obama engaged in more pointed criticism when he chastised the Supreme Court for its ruling in Citizens United during the 2010 State of the Union address. “With all due deference to separation of powers, last week the Supreme Court reversed a century of law that, I believe, will open the floodgates for special interests, including foreign corporations, to spend without limit in our elections." But even this criticism avoided challenging the legitimacy of the court’s decision—or insulting individual judges—even though the case was a major policy defeat. In fact, President Obama urged “Democrats and Republicans to pass a bill that helps correct some of these problems.” He also stated that he would “love to see some constitutional process that would allow us to actually regulate campaign spending the way we used to, and maybe even improve it.” The criticism of the decision was sharp, but the president opined that the ultimate remedy was through the policymaking process.

It’s also worth noting that presidents of both parties have, at times, threatened to undermine the authority of the third branch—either by signaling a willingness to ignore a judgment with full knowledge that the courts can do little to enforce their decisions, or threatening impeachment of a judge who issued a decision with which Members of Congress disagreed.

During the height of the Watergate crisis in 1973, and facing a subpoena from special prosecutor Archibald Cox to turn over taped conversations, the White House said the President would comply with a “definitive” decision of the Supreme Court, “just [as] in other matters.” While the statement was framed to seem like a routine affirmation that the President would obey the courts, it raised the troubling possibility that he could ignore a court ruling he deemed non-definitive, or that he could refuse to follow a lower court order. Over the next several months, Nixon declined to define what he would consider to be a definitive ruling, instead musing, “when we come to the Supreme Court, the question there is what kind of an order is the Supreme Court going to issue, if any?” In response, Senator Ted Kennedy called for Nixon to be impeached if he defied a court order. Ultimately, the Supreme Court ruled unanimously against Nixon, who obeyed the order and thus ended that potential crisis.

Nearly three decades later, in a similarly unsettling episode, several Members of Congress from both sides of the aisle threatened United States district judge Harold Baer with impeachment—and President Clinton hinted that he would seek Baer’s resignation—after the judge issued a pretrial ruling excluding evidence in a drug case.

Some might argue that these examples prove that Trump’s comments are just another example of a president engaging in political speech. But past instances of presidents inappropriately threatening the judiciary do not excuse it now. Such threats risk inhibiting judges from conscientiously carrying out their duties, let alone emboldening future and more egregious threats to their independence, including in the states.

Indeed, one need only look to the saga that unfolded in Pennsylvania just last week to see this threat realized. Following the Pennsylvania Supreme Court’s ruling invalidating the state’s gerrymandered Congressional map on state constitutional grounds, State Senate President Pro Tempore Joe Scarnati not only excoriated the ruling, but also refused to comply with the court’s order for the legislature to turn over districting data. A few days later, state representative Cris Dush went even further and called for impeachment of the five justices who voted down the gerrymander—an action traditionally and appropriately reserved for misbehavior, not as a means to remove from office those with whom one disagrees.

The fact is that most modern presidents have understood the role of the courts as a check on legislative and executive powers. Past presidents have avoided casting doubt on individual judges’ competence to hear a case fairly, let alone the integrity of the entire court system. And in the face of adverse court decisions, many have referenced the imperative to seek redress through other constitutional means and not to suggest that a judge is not, in fact, a judge and a member of a co-equal branch of government.

President Trump’s comments and the recent ordeal in Pennsylvania perhaps reflect a broader crisis in civic life: namely, a profound misunderstanding of how the judiciary is different—and independent—from the other two political branches of government. As Chief Justice Roberts opined at his confirmation hearing, “Judges and justices are servants of the law, not the other way around. Judges are like umpires. Umpires don’t make the rules; they apply them.” While liberals and conservatives will quarrel over what the application of the law should be, the fact remains that the courts exist to interpret the law. This obligation is quite apart from the president and Congress. And it is a responsibility requiring great fortitude and independence from the political whims of the day, as judges must address questions concerning the very legality of the government’s conduct. Since the early days of our Republic, the judicial branch was established as check on overreach by the other branches; as Alexander Hamilton set forth in Federalist 78, “[i]ndependence of the judges may be an essential safeguard against the effects of occasional ill humors in the society.”

In isolation, President Trump’s barbs at the courts are worrying. But to make matters worse, the media often amplifies a message to politicize the judiciary. Commentators have begun to use explosive language in response to court decisions they disagree with, such as labeling courts that issue rebukes to the administration as part of a “judicial resistance,” or calling lower decisions that circumscribe executive action as a “judicial coup”—much akin to the language used by dictators in other parts of the world to gut judicial independence. Reporters and commentators also frequently identify federal court judges in their reporting by the party of the president that nominated the judge (notwithstanding the role of Republicans and Democrats in the Senate in confirming all nominees).

This is a dangerous mix that, at best, will only diminish the public’s faith in the judiciary. On the more alarming end of the spectrum, the President’s statements might be a precursor to a confrontation between the two branches of government. Or, perhaps most concerning, these attacks on the courts could be symptomatic of a broader assault on our democratic institutions, such as attacks against journalists and news outlets. As a new report on the President’s treatment of the third branch recently noted, attacks on the judiciary also “echo those occurring in other countries experiencing the rise of authoritarianism.”

So far, President Trump has been unwilling to cross into outright defiance of the courts. But what will his response be in the face of a national crisis—like a terrorist attack—and a subsequent ruling that limits his authority in that context? As one commentator recently noted following the President’s barrage of tweets attacking the courts and defending the “travel ban” last June, “The President has made it clear that he doesn’t much respect the courts, but will he, ultimately, obey them? Where, the President might ask, is the Supreme Court’s power to enforce anything?”

Most Americans understand that the courts play an important and necessary role in protecting their individual rights, protecting them from government abuse, and protecting contractual obligations. It is a quintessential feature of the American experience that individuals, businesses, and others can turn to the legal system for redress. Our courts serve as a vital check on government power, and we all have a stake in ensuring their legitimacy—whether we are liberal or conservative, populist or libertarian. But the courts don’t have a police force to enforce their rulings. It is, therefore, incumbent on our leaders to act responsibly to defend—rather than to disparage—the vital role of the courts in safeguarding our Constitution.