About that friend request from a name you don’t quite recognize . . .

The Massachusetts Supreme Judicial Court ruled against a man who argued that his charge was unlawful because the evidence that led to his arrest was from videos on his private Snapchat account. The decision sparked a fevered debate about right to privacy in the social media era.Gabby Jones/Bloomberg

The state’s highest court ruled Monday that a Snapchat story recorded by a Boston police officer who friended a suspect using a pseudonym — and then used the clip to charge him in an illegal gun case — did not violate the privacy rights of the man who posted the video.

The unanimous Supreme Judicial Court decision offered what legal experts said was a middle-of-the-road perspective about just what is private, particularly on social media meant to be ephemeral like Snapchat.

The justices rejected an argument from Averyk Carrasquillo that he had a right to privacy in this instance because his Snapchat account was set as “private,” and they rejected an argument from prosecutors that “the act of posting any content to a social media account de facto eliminates any reasonable expectation of privacy.”

Instead they said that the particular circumstances of this case didn’t meet their standards for what constitutes a private arena and affirmed a lower court decision that police had the authority to use the video as evidence against Carrasquillo.

The court also concluded that since Carrasquillo did not have a reasonable expectation of privacy in the content that he shared, “no search in the constitutional sense occurred.”

Ruling in favor of Carrasquillo would require police officers to always identify themselves as when they investigate criminal activity, “thus rendering ‘virtually all undercover work’ unconstitutional,” Justice Frank M. Gaziano wrote on behalf of the court.

“This we decline to do.”

In April 2017, according to court records, Carrasquillo allowed Officer Joseph Connolly’s undercover account — a pseudonym with the default picture — to follow his private Snapchat.

In May of that year, he posted a video of himself for an audience of about 100 Snapchat friends. The video showed Carrasquillo from the waist down, pulling a gun in and out of his pocket. Officers began surveilling near the Dorchester weightlifting gym where he worked, saw him wearing the same clothing as in the video, and searched him. They found a revolver in the same pants pocket shown in the Snapchat story, which was automatically deleted 24 hours after it posted.

Carrasquillo was arrested for possessing the gun without a license.

In 2019, he pleaded guilty to two charges. On one of them, he was sentenced to one year of probation, with the condition that he get a GED and seek full-time employment.

However, Carrasquillo appealed the use of the Snapchat video as evidence in the case, his lawyers arguing that the officer encroached on his right to privacy by pretending to be someone else in order to access his social media. His lawyers also moved to declare the seizure of Carrasquillo’s gun in the arrest as unconstitutional, a motion that was denied in the lower courts and wasn’t challenged in the Supreme Judicial Court.

His lawyers and some civil liberties groups argued that his Fourth Amendment privacy protections were infringed upon, and that new technology is only making it easier to access private social media accounts.

The Massachusetts Association of Criminal Defense Lawyers backed Carrasquillo in an amicus brief that called the Boston Police Department’s undercover activity “sinister,” arguing that the practice of monitoring private social media accounts threatened Carrasquillo’s individual freedom.

“Unbounded government surveillance of private communications reaches far beyond the rights of the surveilled,” they wrote.

While the ACLU of Massachusetts did not take a formal position on the case, the group said it was heartening to see the Supreme Judicial Court acknowledge a person’s expectation of a right to privacy.

“We believe the Court’s holding indicates that it will reach a different conclusion when the facts are different — but ultimately, in the wake of this ruling, every internet user in Massachusetts should be careful about whom they allow to access their private social media posts, accounts, and groups,” said Kade Crockford, the Technology for Liberty program director at the state ACLU.

Prosecutors and criminal law experts saw the decision as a commonsense approach to a new problem law enforcement officials are navigating in the era of social media.

Suffolk District Attorney Kevin Hayden praised the decision.

“We appreciate the careful, reasoned decision by the SJC and agree that the defendant did not have an expectation to privacy under the circumstances presented in this case,” he said in a statement.

Carasquillo’s lawyer declined to comment.

Rosanna Cavallaro, a criminal law professor at Suffolk University Law School said Carrasquillo’s argument was “an uphill battle.”

Social media is performative, she said, and it’s “bad judgement” to assume a private post is truly private.

“I think the one toehold he may have had is this notion that Snapchat is here and gone,” Cavallaro said. “But we know that it’s an illusion, and it’s an illusion that came back to bite him.”

Correction: An earlier version of this story incorrectly said that the ACLU of Massachusetts’ took a position on a key argument of the defendant in a privacy case decided by the Supreme Judicial Court. The ACLU did not take a formal position on the case.