On Tuesday morning, CNN announced it has filed suit against the Trump administration, arguing that the revocation of Jim Acosta’s White House credentials “violates CNN and Acosta’s First Amendment rights of freedom of the press, and their Fifth Amendment rights to due process.” The piece below, which was written before the suit had been filed, explains why CNN should win that suit.

CNN is considering suing the Secret Service to restore the White House press pass the government pulled from reporter Jim Acosta at President Donald Trump’s behest. CNN should bring suit. As leading First Amendment lawyer Floyd Abrams stated, CNN has a strong case: An appellate court precedent all but mandates a ruling in the broadcaster’s favor. In addition, a suit is necessary to vindicate foundational First Amendment principles. The president is trying to intimidate other journalists by threatening to withdraw additional press credentials from reporters whose stories he dislikes.

It is plain that Trump ordered Acosta’s credentials stripped in retaliation for the content of his speech. The entire incident that led to Acosta’s credentials being revoked—including the president’s direction that an intern seize the microphone—was the product of the president’s effort to silence Acosta after he had the temerity to ask questions about two topics Trump was intent upon avoiding: the veracity of Trump’s unsupported assertions during the campaign about an immigrant “caravan” that remains hundreds of miles from the U.S. border, and whether Robert Mueller is about to issue new indictments. In the terminology of First Amendment law, the president engaged in viewpoint discrimination.

The White House contends Acosta was barred because he is a security risk. This claim is grounded on the absurd suggestion that the correspondent assaulted, or otherwise engaged in improper physical contact with, a White House intern. The intern tried, at the president’s behest, to rip a microphone out of Acosta’s hands mid-question during a post-election press conference on Wednesday, and Acosta inadvertently touched her arm in the process. The only “evidence” for the assault assertion is a manipulated video that White House press secretary Sarah Sanders obtained from a website maintained by conspiracy theorist Alex Jones.

The president’s own words undermined the White House’s efforts to manufacture a constitutionally permissible rationale for Trump’s action. During the press conference, Trump repeatedly railed against CNN and Acosta, challenging Acosta’s qualifications as a journalist, as well as his personal qualities, and calling him a “rude, terrible person” who “should not be working for CNN.” Trump also volunteered that an NBC correspondent who had the temerity to vouch for Costa was “not the best.”

Trump also admitted on Friday that Acosta’s press pass was pulled because he does not “treat the presidency with respect” and threatened to withdraw passes from other journalists he considers belligerent questioners. He went on to hurl insults at another reporter, April Ryan, a respected veteran White House reporter who is black and whom he had refused to allow even to pose a question during Wednesday’s press conference. On Friday, Trump also verbally abused another black journalist, Abby Phillip (also of CNN), calling her entirely reasonable question about the new acting attorney general and the Mueller investigation “stupid.”

The U.S. Court of Appeals for the District of Columbia Circuit concluded nearly 41 years ago that the Secret Service cannot deny a journalist White House press credentials absent a compelling purpose—and certainly cannot do so because the president is not a fan of a journalist’s reporting. As Scott Nover reported, the appellate decision concerned Robert Sherrill, a reporter for the Nation magazine who was notorious for challenging both Republican and Democratic politicians, including and especially regarding the Vietnam War. When Sherrill applied for a White House press pass in 1966 (during the Johnson presidency) the Secret Service denied his request, and also denied his renewed application in 1972 during the Nixon administration. When pressed, the government vaguely asserted that he posed a security risk (presumably relying upon some physical altercations and charges in Merrill’s past). The American Civil Liberties Union ultimately brought suit on Sherrill’s behalf, and he prevailed before the appellate court in 1977.

The D.C. Circuit reasoned that the White House’s press facilities have long been made “publicly available” to journalists “as a source of information for newsmen,” and stated that such access is essential to press coverage of the White House and the president. Accordingly, the appellate court reasoned that the First Amendment’s protection of freedom of the press bars the denial of a White House press pass to an individual journalist arbitrarily or for “less than compelling reasons.” Other courts have reached the same conclusion regarding similar governmental attempts to selectively exclude the press, reasoning that the “[e]xclusion of an individual reporter … carries with it ‘the danger that granting favorable treatment to certain members of the media allows the government to influence the type of substantive media coverage that public events will receive,’ which effectively harms the public.” Furthermore, viewpoint-based exclusions of reporters, as Acosta experienced, have repeatedly been rejected as almost categorically unconstitutional because they strike at the heart of the First Amendment.

The Sherrill decision concluded that constitutional due process standards require the Secret Service to explain the standards for press pass denials, give a journalist facing a denial the right to respond, and, if the government stands on its denial decision, mandate that it state the final reasons in writing. The government failed to follow those mandatory procedures before pulling Acosta’s credentials. Even if this procedural misconduct is remedied, it is difficult to imagine the Secret Service successfully defending Trump’s pulling of Acosta’s credentials given both the president’s admission of his improper purpose and the White House’s reliance on manipulated evidence in support of its ex post facto rationalization.

Some have convincingly argued that Trump calculates his attacks on the press to distract from other embarrassing or disturbing events, most recently including his potentially illegal installation of an acting attorney general and the routing of many GOP candidates in the recent election. While the press should do its best to prevent the president from succeeding in making his abuse of journalists the center of attention, square attacks upon the newsgathering process—like that visited on Acosta—must not go unanswered.