Chrome users who declined to sync their Google accounts with their browsing data secured a big privacy win this week after previously losing a proposed class action claiming that Google secretly collected personal data without consent from over 100 million Chrome users who opted out of syncing.

On Tuesday, the 9th US Circuit Court of Appeals reversed the prior court’s finding that Google had properly gained consent for the contested data collection.

The appeals court said that the US district court had erred in ruling that Google’s general privacy policies secured consent for the data collection. The district court failed to consider conflicts with Google’s Chrome Privacy Notice (CPN), which said that users’ “choice not to sync Chrome with their Google accounts meant that certain personal information would not be collected and used by Google,” the appeals court ruled.

Rather than analyzing the CPN, it appears that the US district court completely bought into Google’s argument that the CPN didn’t apply because the data collection at issue was “browser agnostic” and occurred whether a user was browsing with Chrome or not. But the appeals court—by a 3–0 vote—did not.

In his opinion, Circuit Judge Milan Smith wrote that the “district court should have reviewed the terms of Google’s various disclosures and decided whether a reasonable user reading them would think that he or she was consenting to the data collection.”

“By focusing on ‘browser agnosticism’ instead of conducting the reasonable person inquiry, the district court failed to apply the correct standard,” Smith wrote. “Viewed in the light most favorable to Plaintiffs, browser agnosticism is irrelevant because nothing in Google’s disclosures is tied to what other browsers do.”

Smith seemed to suggest that the US district court wasted time holding a “7.5-hour evidentiary hearing which included expert testimony about ‘whether the data collection at issue'” was “browser-agnostic.”

“Rather than trying to determine how a reasonable user would understand Google’s various privacy policies,” the district court improperly “made the case turn on a technical distinction unfamiliar to most ‘reasonable'” users, Smith wrote.

Now, the case has been remanded to the district court where Google will face a trial over the alleged failure to get consent for the data collection. If the class action is certified, Google risks owing currently unknown damages to any Chrome users who opted out of syncing between 2016 and 2024.

According to Smith, the key focus of the trial will be weighing the CPN terms and determining “what a ‘reasonable user’ of a service would understand they were consenting to, not what a technical expert would.”

The same privacy policy last year triggered a Google settlement with Chrome users whose data was collected despite using “Incognito” mode.

Matthew Wessler, a lawyer for Chrome users suing, told Ars that “we are pleased with the Ninth Circuit’s decision” and “look forward to taking this case on behalf of Chrome users to trial.”

A Google spokesperson, José Castañeda, told Ars that Google disputes the decision.

“We disagree with this ruling and are confident the facts of the case are on our side,” Castañeda told Ars. “Chrome Sync helps people use Chrome seamlessly across their different devices and has clear privacy controls.”

By Holden