The Supreme Court on Thursday unanimously ruled in favor of the National Rifle Association (NRA), stating that a New York government regulator abused her power when she coerced private businesses to blacklist the group following the 2018 mass shooting at Marjory Stoneman Douglas High School in Florida.

The American Civil Liberties Union (ACLU) represented the NRA, arguing that any government attempt to censor an advocacy group because of differing political views violates the First Amendment. The ACLU argued that the group’s rights were violated after former New York Gov. Andrew Cuomo and his chief financial regulator, Maria Vullo, tried to convince banks and insurance companies to deny the gun group financial services.

“The decision confirms that government officials have no business using their regulatory authority to blacklist disfavored political groups,” David Cole, the ACLU’s national legal director and who argued the case for the NRA, said in a statement. “Cuomo and Vullo… sought to punish the NRA because they disagreed with its gun rights advocacy. The Supreme Court has now made crystal clear that this action is unconstitutional.”

The ACLU said that although it “stands in stark opposition to the NRA on many issues,” it was necessary to represent the gun group to ensure First Amendment rights for all advocacy organizations. Civil rights advocates said that if New York were allowed to blacklist a “powerful organization” like the NRA, it would set precedent for government officials to target groups with less influence and especially those that represent marginalized communities.

Justice Sonia Sotomayer wrote in the opinion “Viewpoint discrimination is uniquely harmful to a free and democratic society. The First Amendment prohibits government officials from wielding their power selectively to punish or suppress speech.”

The ruling in NRA v. Vullo reversed a previous decision by the U.S. Court of Appeals, which ruled that it was reasonable for New York state officials to warn about enhanced social responsibility following the Parkland, Florida shooting, in which a gunman killed 17 students and staffers. The court had also said that Vullo’s guidance was not a directive but an expression of her political point of view.

“This is a landmark victory for the NRA and all who care about our First Amendment freedom,” William A. Brewer III, counsel to the NRA, said in a statement. “The opinion confirms what the NRA has known all along: New York government officials abused the power of their office to silence a political enemy. This is a victory for the NRA’s millions of members and the freedoms that define America.”

The NRA in 2018 sued Maria Vullo, who was then the superintendent of the New York Department of Financial Services, claiming that she used her regulatory power over banks and insurance companies to push them to sever ties with the NRA and “other gun promotion” groups. According to the ACLU, Vullo sought to punish the organization because she did not agree with its political advocacy.

Vullo issued “formal guidance” to every bank and insurance company in New York, asking them to “fulfill their corporate social responsibility,” promising leniency to insurers who stopped doing business with the NRA and requiring others to never provide the gun group with services, according to the complaint.

A district court first ruled that the NRA’s allegations were sufficient to claim a First Amendment rights violation. Then the appeals court reversed the decision stating that her actions were justified because the NRA’s views are widely unpopular in New York before the Supreme Court reviewed the case.

Vullo’s representative Neal Katyal said they are “disappointed” by the ruling and denied claims that government officials threatened or coerced the private companies, according to CBS News.

“Ms. Vullo did not violate anyone’s First Amendment rights,” he said. “Ms. Vullo enforced the insurance law against admitted violations by insurance entities, and industry letters such as those issued by Ms. Vullo are routine and important tools regulators use to inform and advise the entities they oversee about risks.”

Before NRA v. Vullo, there was only one other case — Bantam Books v. Sullivan — defending informal efforts by government officials to suppress or punish free speech activity, according to the ACLU. The latter case is more than 60 years old and circuit courts are divided in applying it, making the most recent decision a “critically important win,” civil rights advocates said.

“By rejecting the Second Circuit’s dangerous reasoning in this case and strengthening the protections created in Bantam Books more than 60 years ago, the Supreme Court now has an opportunity to protect the market of ideas by safeguarding all advocacy groups from government overreach,” the ACLU said.