It was designed as a convenient way to keep track of keys, wallets, and bags. But for a growing number of people, Apple‘s AirTag has become an instrument of harassment and stalking. Now, the tech giant is facing a major legal challenge over allegations that it failed to safeguard against the device’s nefarious potential.

On Friday, a federal judge in San Francisco dealt a blow to Apple, ruling that a class-action lawsuit targeting the company’s much-touted AirTag can proceed. While U.S. District Judge Vince Chhabria dismissed several claims, he allowed three plaintiffs to move forward with accusations of negligence and product liability against the iPhone maker.

The plaintiffs, among about three dozen women and men who joined the lawsuit, allege a harrowing pattern: the small, coin-sized AirTags were secretly slipped into their belongings, allowing stalkers and abusers to track their every movement through the devices’ network of iOS users. Their complaint argues that Apple was aware of these risks yet failed to implement sufficient safeguards, making the $29 trackers a “weapon of choice” for those bent on surveillance and harassment.

“Apple may ultimately be right that California law did not require it to do more,” wrote Chhabria in his 19-page ruling. “But that determination cannot be made at this early stage.”

Unveiled in April 2021, AirTags quickly captured the public’s imagination as a simple, affordable way to keep tabs on prized possessions using Apple’s comprehensive “Find My” network. But critics and advocacy groups soon raised alarms about the potential for abuse, warning that the trackers could easily be exploited to surreptitiously monitor someone’s movements without their consent.

Apple maintains that it engineered “industry-first stalker-proofing” measures into AirTags, such as automatic alerts warning users if an unexpected tracker seems to be traveling with them. The company urged Judge Chhabria to dismiss the lawsuit, arguing that holding it liable would amount to a “radical rewriting of California’s products liability law.”

Those arguments, however, failed to persuade the judge that Apple could skirt responsibility at this stage of the litigation. “When they were stalked, the problems with the AirTag’s safety features were substantial,” Chhabria wrote of the three plaintiffs advancing their claims, “and those safety defects caused their injuries.”

The high-stakes case underscores an increasingly urgent debate around smart trackers and a host of other tech products that can jeopardize privacy and personal safety when deployed maliciously. Tile, a competitor to AirTags, is facing similar allegations in Arizona over its line of tracking devices.

As ubiquitous as they’ve become, from kids’ backpacks to airline luggage, these tiny gadgets have opened Pandora’s box of ethical concerns—and now, potentially massive legal exposure for their makers.

Apple did not respond to a request for comment on the ruling, which clears the path for the negligence claims to head toward a trial unless a settlement can be reached. For the anonymous plaintiffs, their aim is to hold the tech behemoth accountable for endangering those it claims to protect.

“This case should serve as a wake-up call,” said their lawyer. “These companies need to prioritize consumer safety over commercial interests.”