Your Instagram friend could secretly be a police officer, and that's totally legal, at least in New Jersey. In an opinion from earlier this month, district court judge William Martini responded to a request by Daniel Gatson, who is accused of running a lucrative jewelry theft ring that was busted by the FBI in 2013. Among many other requests to suppress evidence of cellphone location data, seized physical evidence, and phone conversations, Gatson asked for the court to throw out his social media history: namely, pictures from a private Instagram account, which law enforcement officers had accessed by creating a fake account and friending him.

"No search warrant is required" to go undercover on Instagram

Social media, especially places where people might feel safe enough to post secrets, have become a standard tool for law enforcement. In 2013, the NYPD shut down an illegal gun-selling operation after seeing pictures of weapons and cash on Instagram. Prosecutors have used tweets to show intent in murder charges, and Facebook messages were central to a New York gang raid last year. In some cases, the information was public. In others, though, it was restricted to friends, so police had to either find informants or actively create fake accounts and gain a suspect's trust. This might not be a complicated process: it's not difficult to make someone think you have friends in common. But they're still gaining information under false pretenses, and defendants have sued on those grounds, saying it constituted an invasive search.

On a site like Facebook, which requires real names, it would at least violate community standards; Buzzfeed reported on such a case in October. Instagram, though, has much looser standards, and Judge Martini shut the request down quickly. "No search warrant is required for the consensual sharing of this type of information," he wrote. Besides the statement that law enforcement used an "undercover account" to become friends with Gatson, there's little information about the move in either this or other court filings. It appears far less important to the case than phone surveillance — police gathered location data to put Gatson near the scene of burglaries and tapped phone conversations between him and other alleged conspirators.

We're still figuring out how the law should treat social media, especially when it comes to nebulous online crimes like threats. But Martini was able to refer to a case from 2012 that was similarly favorable to police: a New York district court decision saying that if a Facebook friend is working with the police, it's entirely legal for them to share what you post.