The First Amendment makes it unconstitutional for government officials to retaliate against you because they dislike your speech. At the same time, federal law gives you the right to sue state officials for compensation if they violate constitutional rights such as your right to free speech. But on Tuesday, the Supreme Court invented a rule that will often allow police officers to arrest people in retaliation for disfavored speech without liability.

By enabling police officers to target viewpoints they dislike with near impunity, the decision could be catastrophic for protesters and the press. The justices, meanwhile, didn’t even try to ground their decision in the text or history of the statute they were interpreting. Instead, the court was surprisingly frank about its rationale: The justices simply don’t want police officers to have to defend themselves in court against these types of allegations.

In Nieves v. Bartlett, a divided court ruled that individuals can’t sue police officers for retaliatory arrest if those officers had probable cause to arrest them for any crime, no matter how minor—and that’s true even if the real reason for the arrest was speech the officers didn’t like. In other words, if you are jaywalking in violation of a local ordinance, officers can arrest you without fear of liability even if they’re making the arrest only because you’re participating in a Black Lives Matter demonstration or wearing a “Make America Great Again” cap.

Because local laws are full of minor infractions, like “loitering,” that are frequently violated without incident, police will often have a pretext to arrest people engaged in speech the officers don’t like. By immunizing such abuse, Nieves may have devastating effects on demonstrators, press photographers, and anyone who wants to exercise their speech rights in public, like the right to film the police or verbally challenge officer misconduct. The power to arrest is a potent tool for suppressing speech because even if charges are later dropped, arrestees must undergo the ordeal—and dangers—of being booked and jailed, and they may have to disclose the arrest on future job and housing applications, among other ramifications.

Congress long ago recognized that making officers financially liable is the most effective way to deter such misconduct. And that’s why a federal law called Section 1983 enables lawsuits against state officers for violating constitutional rights. This landmark statute was enactedduring Reconstruction when Southern states were refusing to respect basic liberties. As one congressman said, the federal government could not directly compel these states to fall in line, but it could “deal with the offenders” by giving “the injured party … an original action in our Federal courts.” Section 1983 therefore authorizes suits for violations of “any rights” that are “secured by the Constitution.”

The Nieves decision takes a red pen to the statute Congress wrote, based on some justices’ fear that police actions taken “during a legitimate arrest could land an officer in years of litigation.” That objection, though, was already made in the proper forum—Congress—when it debated and passed Section 1983 many years ago. Opponents claimed that “this bill … puts in jeopardy the officers of the States, though in the conscientious discharge of their duties” and would lead to “vexatious, expensive, and protracted litigation.” Those objections failed in the political process. Stepping into Congress’ role nearly a century and a half later, the Roberts court revived them.

There is no evidence that Congress wanted the statute to be interpreted like this.

Things were clearly headed in this direction during oral argument last fall, where the justices’ questions suggested that they viewed the case as an opportunity to decide what rules would be best for society. Justice Stephen Breyer made no secret of the fact that he was looking for a “compromise” that would sacrifice some First Amendment rights to limit the number of lawsuits against the police. For an hour, the justices debated the merits of various approaches like legislators crafting a bill. Missing was any substantial discussion of the meaning of the First Amendment or the text and history of Section 1983.

In response, the plaintiff’s counsel had to remind the justices of a truism they have often repeated: If a law produces socially undesirable results, it’s the job of Congress—not the court—to amend that law. This prompted a stunning but revealing question from Chief Justice John Roberts: “What law is Congress supposed to change?” Amid all the policy debate, it seemed the chief had completely forgotten this case was about interpreting a federal statute.

Unfortunately, six months of reflection since that argument didn’t change things. So how did the court attempt to justify the new rule it announced?

First, it relied on an earlier decision that imposed a similar rule for retaliatory prosecutions. But that earlier case involved federal, not state, officers, and thus had nothing to do with the statute the court was supposed to be interpreting in Nieves. Crucially, since a 1971 case found a right to sue federal officials for constitutional violations, the Roberts court has been chipping away at the ability to seek damages from federal officers.

Its justification for that erosion of federal liability? Congress, not the courts, should decide when officials can be sued for compensation. Got that? When Congress has not authorized lawsuits against officials, it’s wrong for the Supreme Court to supplant Congress’ role by allowing such lawsuits. But when Congress has authorized lawsuits, it’s fine for the court to cut back on what Congress has authorized if the justices don’t like the implications.

Second, the justices in Nieves drew a convoluted comparison between First Amendment claims for retaliatory arrest and personal injury torts that are designed to compensate people for unauthorized imprisonment. To win on those tort claims, you have to show there was no probable cause to arrest you. Ergo, the court said, the same should be true for a First Amendment claim.

There is no evidence that Congress wanted the statute to be interpreted like this. As my organization, the Constitutional Accountability Center, explained in an amicus brief, Section 1983 was meant to vindicate the unique rights protected by the federal Constitution—like free speech—not the very different rights protected by state tort law.

Justice Neil Gorsuch, to his credit, was having none of this, insisting in dissent that there is “no legitimate basis for engrafting a no-probable-cause requirement onto a First Amendment retaliatory arrest claim.” Adopting a central point of our amicus brief, Gorsuch explained that “a First Amendment retaliatory arrest claim serves a different purpose” than claims based on a lack of legal authority to arrest and that “that purpose does not depend on the presence or absence of probable cause.”

The only silver lining in all this is that the court did create an exception to its harsh new rule. Even if police have probable cause to arrest, a plaintiff can still prevail by showing that the police “typically exercise their discretion” not to make arrests in similar circumstances. It’s unclear how this vague exception will be applied by the lower courts and whether it will have enough teeth to prevent cops from feeling free to operate with impunity. Gorsuch expressed optimism that the exception would be read broadly and “commonsensically” in future cases. Let’s hope he’s right.