Taylor Swift held a concert at California’s Rose Bowl this past May that was monitored by a facial recognition system. The system’s target? Hundreds of Swift’s stalkers. 
 
 Swift’s facial recognition system was built into a kiosk that displayed highlights of her rehearsals, which would secretly record onlookers’ faces. According to Rolling Stone, which spoke with a concert security expert who observed the kiosk, attendees who looked at the kiosk were immediately scanned. Afterward, the data was sent to a “command post” in Nashville, Tennessee that attempted to match hundreds of images to a database of her known stalkers. 
 
 Surveillance at a concert — a private event — is legal 
 
 US artists haven’t previously been publicized for using facial recognition tech at their concerts. However, the legality of doing so is on the artist’s side: a concert is technically a private event, therefore event organizers can subject concert-goers to almost any kind of surveillance. 
 
 The security measures taken for Swift’s event could be considered extreme, but it’s not the first time facial recognition has been used to look out for unwanted attendees. 
 
 This past April, Chinese police arrested a 31-year-old suspect who was hiding among nearly 60,000 people during a concert at Nanchang International Sports Center. This was made possible by the early stages of China’s own “Xue Liang,” or “Sharp Eyes,” monitoring system, which will be tasked with monitoring the movements of its citizens. 
 
 Back in the US, advancements are also being made with facial recognition technology in big crowds. For example, Ticketmaster envisions replacing tickets with a facial scan that is tied to your seat, and it is further developing the tech. While you might not be scanned going to see the next Marvel film, the movie ticket of the future might just be your face. ||||| Security for Taylor Swift at California’s Rose Bowl in May 2018 included a facial recognition system monitored from almost 2,000 miles away. 
 
 A kiosk set up to show highlights of the singer’s rehearsals secretly recorded the faces of onlookers, which were sent to a “command post” in Nashville, Tennessee that attempted to match those images to hundreds of images of known Taylor Swift stalkers, according to Rolling Stone. 
 
 “Everybody who went by would stop and stare at it, and the software would start working,” Mike Downing, chief security officer at live entertainment security company Oak View Group, who personally attended the event, said. Oak View Group did not immediately respond to a request for comment. 
 
 It’s unknown whether the footage was kept, or if it even identified any real stalkers—and if it did, what happened after they were identified. 
 
 But concert venues are typically private locations, meaning even after security checkpoints, its owners can subject concert-goers to any kind of surveillance they want, including facial recognition. 
 
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– She knew you were trouble when you walked in—and so she installed facial recognition technology to flag you. Per Rolling Stone, Taylor Swift made use in May of a special kiosk at her California Rose Bowl show that secretly scanned concertgoers' faces, then shot those pictures back to a "command post" in Nashville, Tenn. There, the faces were compared with those of "hundreds" of Swift's known stalkers. Intel on the surreptitious spying kiosk, which was showing clips of the pop star rehearsing to lure spectators so their faces could then be photographed, comes via a security expert who says he was invited to watch a demo of the system at the Rose Bowl show by the kiosk manufacturer; Swift's own reps are keeping tight-lipped about it. Mashable calls it a "creepy" yet "understandable" use of the technology, considering the trouble Swift has had with alleged stalkers in the past. Still, it raises a few questions, including whether the photos will be kept, for how long, and what else they might be used for; per Quartz, it's unclear whether any stalkers were identified at the Swift event. The Verge notes that concerts are typically private events, meaning organizers can legally set up practically any kind of surveillance. Swift's fans aren't the only ones who may be undergoing Terminator-like scanning: Rolling Stone notes facial recognition technology is increasingly being used at arenas and stadiums, not only for safety, but also for efficiency—by keeping tabs on how quickly guests move through a venue, event organizers can set up systems to keep the flow streamlined. "It holds a lot of promise," says a rep for Ticketmaster, which plans on tapping the tech. "We're just being very careful about where and how we implement it." (One person who may not be attending a Swift concert anytime soon: President Trump.)