The Supreme Court on Tuesday invalidated a Colorado law that bans so-called “conversion therapy” in talk therapy for LGBTQ patients. The decision found that such laws violate the free speech rights of counselors.

The 8-1 decision reversed a ruling by the U.S. Court of Appeals for the 10th Circuit that upheld the Colorado law as a regulation on professional conduct by medical professionals.

The Supreme Court’s majority opinion, written by Justice Neil M. Gorsuch, held that the state law violated the free speech rights of talk therapy counselor Kaley Chiles by favoring one viewpoint over another.

The First Amendment “safeguards not only popular ideas; it secures, even and especially, the right to voice dissenting views,” Gorsuch wrote.

“Conversion therapy” is a scientifically discredited practice of using therapy to “convert” LGBTQ people to heterosexuality or traditional gender expectations.

Chiles challenged the Colorado law that prohibits any practice that “attempts or purports to change an individual’s sexual orientation or gender identity.” More than two dozen states nationwide have similar laws, and the Trump administration also weighed in, asking the justices to curtail the law.

The state had argued that conversion therapy has not been shown to be effective and that the law applied only to licensed counselors.

But Gorsuch wrote that upholding the law could allow states to adopt laws that went the other way, such as mandating that counselors treat LGBTQ patients as mentally ill.

“A prevailing standard of care may reflect what most practitioners believe today, but it cannot mark the outer boundary of what they may say tomorrow,” Gorsuch wrote.

Justice Elena Kagan, joined by Justice Sonia Sotomayor, wrote a concurring decision stating that the constitutional problems with Colorado’s law were “textbook” but that it is possible a state could write a law differently to regulate talk therapy.

Justice Ketanji Brown Jackson dissented from the decision and wrote that invalidating the law opened up LGBTQ people, particularly children, to potentially abusive practices. Reading a portion of her dissent from the bench, Jackson said the decision undermined states’ ability to prevent counselors from advocating suicide or eating disorders.

“My colleagues’ contrary conclusions are puzzling, for a standards-based healthcare scheme cannot function unless its regulators are permitted to choose sides,” Jackson wrote.

The case is the latest in a series of clashes between state laws protecting LGBTQ people and free speech rights that have reached the Supreme Court in recent years. Two years ago, the court decided in favor of a website designer who argued that Colorado anti-discrimination law would have violated her free speech rights.

The case is Kaley Chiles v. Patty Salazar et al.