WASHINGTON — The Supreme Court ruled on Friday that members of the public in some circumstances can sue public officials for blocking them on social media platforms, deciding a pair of cases against the backdrop of former President Donald Trump’s contentious and colorful use of Twitter.

The court ruled unanimously that officials can be deemed “state actors” when making use of social media and can therefore face litigation if they block or mute a member of the public.

In the two cases before the justices, they ruled that disputes involving a school board member in Southern California and a city manager in Michigan should be sent back to lower courts for the new legal test to be applied.

In a ruling authored by Justice Amy Coney Barrett, the court acknowledged that it “can be difficult to tell whether the speech is official or private” because of how social media accounts are used.

The court held that speech can be viewed as state actions when the official in question “possessed actual authority to speak on the state’s behalf” and “purported to exercise that authority.”

While both officials have low profiles, the ruling will apply to all public officials who use social media to engage with the public.

During October’s oral argument, Trump’s use of Twitter — before it was renamed X — was frequently mentioned as the justices considered the practical implications.

The cases raised the question of whether public officials’ posts and other social media activity constitute part of their governmental functions. In ruling that it can, the court found that blocking someone from following an official constitutes a government action that could give rise to a constitutional claim.

Trump himself was sued when he was president, with the courts ruling against him, noting that he often used his Twitter account to make official announcements. But that lawsuit was tossed out as moot once he left office in January 2021. At that point, Twitter had disabled Trump’s account, although the company’s new owner, Elon Musk, has reversed course as part of a major overhaul that has included changing the site’s name. In other disputes, however, courts have reached other conclusions.

The California case arose after two members of the Poway Unified School District Board of Trustees, Michelle O’Connor-Ratcliff and T.J. Zane, blocked parents Christopher and Kimberly Garnier from commenting on their Facebook page in 2017. O’Connor-Ratcliff also prevented Christopher Garnier from responding to her Twitter posts. Zane has since left office.

The San Francisco-based 9th U.S. Circuit Court of Appeals in 2022 ruled for the couple, upholding a similar decision by a federal judge in the Southern District of California. The appeals court concluded that the elected officials were acting in their official capacities.

The dispute in Michigan began in March 2020, when Port Huron City Manager James Freed, an appointed official whose Facebook page described him as a “public figure,” posted information there about the city’s efforts to deal with the Covid-19 pandemic. After resident Kevin Lindke posted comments criticizing the city’s response, Freed blocked him.

Freed argued that the no-longer-active Facebook page was a personal page that he used to share pictures of his family and comment on his daily activities. The 6th U.S. Circuit Court of Appeals, upholding a lower court decision, agreed in a June 2022 decision, ruling that Freed was not acting in his official capacity and that therefore his Facebook activity did not constitute state action.

Freed’s page was somewhat different from the ones at issue in the school board case because it included a lot more personal content, making it much less clear whether it was an official page.

The court is wrestling with a whole series of social media-related free speech issues in its current term, which runs until June.