In a 6-3 decision along ideological lines siding with Texas, Justice Clarence Thomas wrote in the majority opinion that the law "only incidentally burdens the protected speech of adults," and therefore did not require "strict scrutiny" from the Court.
But advocates for free speech and online security have warned that such laws—which have passed in 24 states—have the potential to be much more invasive, both to personal expression and privacy.
Following the ruling, the American Civil Liberties Union (ACLU) decried the Court's decision as "a blow to freedom of speech and privacy."
"The Supreme Court has departed from decades of settled precedents that ensured that sweeping laws purportedly for the benefit of minors do not limit adults' access to First Amendment-protected materials," said Cecillia Wang, national legal director of the ACLU. "The legislature claims to be protecting children from sexually explicit materials, but the law will do little to block their access, and instead deters adults from viewing vast amounts of First Amendment-protected content."
The ACLU's concerns echoed those expressed in Justice Elena Kagan's dissenting opinion, in which she said the court should have applied "strict scrutiny," which would have required the bill to use the least restrictive means possible to meet its goal. Applying strict scrutiny is standard in cases involving content related restrictions on expression, and has been used in past cases related to obscenity.
"No one doubts that the distribution of sexually explicit speech to children, of the sort involved here, can cause great harm," she added. "But the First Amendment protects those sexually explicit materials, for every adult. So a state cannot target that expression, as Texas has here, any more than is necessary to prevent it from reaching children."
During oral arguments in January, Kagan warned of the potential "spillover danger" if the court were to weaken strict scrutiny for free expression cases.
"You relax strict scrutiny in one place," she said, "and all of a sudden, strict scrutiny gets relaxed in other places."
Friday's ruling comes as red states have introduced laws increasingly cracking down on public discussion of sex and gender.
These have included laws banning sexual education or the discussion of LGBTQ+ identities in schools, bans on books containing "divisive" topics including sex and gender, and bans on drag shows in public spaces. Many states have also introduced laws allowing parents to challenge books containing "divisive" concepts, including discussions of sexuality and LGBTQ+ identity.
On Friday, the Supreme Court also ruled on religious liberty grounds in favor of parents' rights to opt their children out from classes with storybooks involving LGBTQ+ characters.
"As it has been throughout history, pornography is once again the canary in the coal mine of free expression," said Alison Boden, executive director of the Free Speech Coalition, which was one of the plaintiffs in the Texas case.
Beyond burdening adults' free expression, critics warned that requiring photo identification poses a privacy risk to porn viewers.
The conservative justices defended the law as tantamount to others that require identification to access alcohol or to enter adults-only spaces. In his majority opinion, Thomas wrote that the law is "appropriately tailored because it permits users to verify their ages through the established methods of providing government-issued identification and sharing transactional data."
However, Kagan argued in her dissent that requiring photo ID for online activity is fundamentally different because the user has no idea if their identifying information is being tracked or logged.
"It is turning over information about yourself and your viewing habits—respecting speech many find repulsive—to a website operator, and then to… who knows?" she said.
Evan Greer, founder of the online privacy advocacy group Fight for the Future, wrote on BlueSky that the ruling bodes ill for internet privacy more generally.
"This is bad in a variety of ways that have nothing to do with porn and everything to do with expanding invasive surveillance of every single internet user, including all adults," Greer said.
