The decision hands a win to President Joe Biden's administration and top government agencies ahead of the presidential vote in November, allowing them to continue notifying major platforms such as Facebook and X about what they deem as false or hateful content.
The justices, voting 6-3, threw out the case on the grounds that the challengers -- including two states and social media users -- had not suffered a direct injury that provided a legal standing to sue.
"The plaintiffs, without any concrete link between their injuries and the defendants' conduct, ask us to conduct a review of the years-long communications between dozens of federal officials, across different agencies, with different social-media platforms, about different topics," Justice Amy Coney Barrett wrote for the majority.
"This court's standing doctrine prevents us from (exercising such) general legal oversight of the other branches of government."
The decision was a setback for conservative advocates who allege that the government has pressured or colluded with major platforms to censor right-leaning content under the guise of fighting misinformation.
"For months, high-ranking government officials placed unrelenting pressure on Facebook to suppress Americans' free speech," wrote Justice Samuel Alito, who dissented along with Justices Clarence Thomas and Neil Gorsuch.
"Because the court unjustifiably refuses to address this serious threat to the First Amendment, I respectfully dissent," Alito added, asserting that one of the plaintiffs had a legal standing to sue.
'Pivotal' timing
Firebrand Republican lawmaker Jim Jordan, who has steered a sweeping legal offensive against misinformation researchers, also voiced disappointment over the ruling.
"The First Amendment is first for a reason, and the freedom of expression should be protected from any infringement by the government," Jordan, chair of the House Judiciary Committee, said in a statement.
"While we respectfully disagree with the court's decision, our investigation has shown the need for legislative reforms... to better protect Americans harmed by the unconstitutional censorship-industrial complex."
The case stems from a lawsuit brought by the Republican attorneys general of Louisiana and Missouri, who alleged that government officials went too far in their bid to get platforms to combat vaccine and election misinformation, violating First Amendment free speech rights of social media users.
Last year, a lower court restricted top officials and agencies in Biden's administration from meeting and communicating with social media companies to flag what they considered harmful posts.
The lower court order applied to the White House and a slew of agencies such as the Federal Bureau of Investigation, the State Department, the Justice Department as well as the Centers for Disease Control and Prevention.
Some experts in misinformation and First Amendment law criticized the lower court ruling, saying the authorities needed to strike a balance between calling out falsehoods and veering towards censorship or curbing free speech.
The lawsuits intended to "weaponize" the First Amendment, which would have undermined the government's ability to defend the United States against election interference and disinformation campaigns, watchdog group Accountable Tech said as it welcomed Wednesday's ruling.
"Cooperation between the government and platforms about foreign influence campaigns, election integrity and public health emergencies is essential to preserving public safety and a healthy democracy," the group said in a statement.
"This decision comes at a pivotal time just months before the November election, as tech companies cut back on trust and safety teams and are recklessly deploying new AI products that are contributing to accelerated online disinformation."
