A coalition of free-press advocates is taking on the president.

President Donald J. Trump’s frequent threats and hostile acts directed toward journalists and the media are not only offensive and unbecoming of a democratic leader; they are also illegal. In the Trump era, nasty rhetoric, insults and even threats of violence have become an occupational hazard for political reporters and commentators. To be sure, a good portion of President Trump’s verbal attacks on journalists and news organizations might be considered fair game in this bare-knuckled political moment. The president has free-speech rights just like the rest of us, and deeming the news media “the enemy of the American people” and dismissing accurate reports as “fake news” are permissible under the First Amendment.

But the First Amendment does not protect all speech. Although the president can launch verbal tirades against the press, he cannot use the powers of his office to suppress or punish speech he doesn’t like. When President Trump proposes government retribution against news outlets and reporters, his statements cross the line. Worse still, in several cases it appears that the bureaucracy he controls has acted on his demands, making other threats he issues to use his governmental powers more credible. Using the force of the presidency to punish or suppress legally protected speech strikes at the heart of the First Amendment, contravening the Constitution. Presidents are free to mock, needle, evade and even demean the press, but not to use the power of government to stifle it.That is why this week PEN America, an organization of writers that defends free expression, together with the nonprofit organization Protect Democracy and the Yale Law School Media Freedom and Information Clinic, is filing suit in federal court seeking an order directing the president not to use the force of his office to exact reprisals against the press.

While the president’s actions are unprecedented, the law here is established. A 2015 judicial opinion by the Seventh Circuit’s (now-retired) Judge Richard Posner makes clear that “a public official who tries to shut down an avenue of expression of ideas and opinions through actual or threatened imposition of government power or sanction is violating the First Amendment.” Similarly, a 2003 Second Circuit opinion found that the First Amendment was violated when an official’s statements “can reasonably be interpreted as intimating that some form of punishment or adverse regulatory action will follow the failure to accede to the official’s request.’”

President Trump has engaged repeatedly in precisely the kind of behavior those courts have found unlawful.

After repeatedly attacking CNN’s news coverage as “fake,” “garbage” and “terrible” and personally pledging to block a proposed merger of its parent company, Time Warner, with AT&T, the Trump administration opposed the deal, a vertical merger that would not normally attract antitrust scrutiny. The government denied that retaliation was at work and the court did not assess that claim. But the judge rejected the government’s challenge and approved the merger with no conditions imposed, citing the government’s failure to adduce “economic evidence of any kind” and reliance on “bare conjecture” as the basis for its case.

Trump has also repeatedly attacked the Washington Post and threatened to target its owner Jeff Bezos’s biggest holding, Amazon. This spring the president followed through on his threats, ordering the Postal Service to review rates for the online shopping behemoth. Coming in the wake of the president’s eruptions directed at the Post, that order too appears to be punitive.polit

In other cases, too, the president seems to be retaliating against individuals for their coverage. Trump threatened to withdraw the press credentials of reporters who criticized him; in August CNN’s Kaitlan Collins was barred from a Rose Garden press conference for asking questions the White House judged impertinent.

Others in the media cannot help but take notice that an angry president may strike back. When we have consulted our members, writers and journalists working across the U.S., they have told us they take into account in their writing that criticism of the administration might put them at risk. Many media outlets and correspondents are pressing forward fearlessly, making this a heyday for certain types of hard-hitting coverage. But individual writers, especially without the protection of a big media company, may think twice before publishing pieces that could land them in the White House’s crosshairs. Moreover, while intrepid journalists may be willing to work under threat from the highest levels of their government, here in the United States they should never have to.

Curtailing the president’s violations of the First Amendment is unlikely to halt some of its most dangerous ripple effects. The last few months have brought violent attacks on journalists, some clearly inspired by the president’s invective. In August a man was arrested for threatening to murder Boston Globe journalists parroted the president’s “enemy of the people” language. White House radio reporter April Ryan, the New York Times’ Bret Stephens, CNN’s Andrew Kaczynzki and others have received death threats.

President Trump’s tirades against the press are by now routine, and may seem to fit right in with our no-holds-barred culture of polarized punditry and bluster. But the president of the United States isn’t just another talking head. It is vital that courts weigh in to underscore that no matter what a given president may think and say, a free press is an essential pillar of our democracy. A court could affirm that by reminding President Trump that his freedom of speech does not extend to threatening to use the powers of his office against the press.

Our news media is right to keep their heads down, ignore the insults and remain focused on journalism. But that shouldn’t mean the president’s First Amendment violations go unchallenged. It is up to those of us who depend upon a free press to rise in defense of it.