Facebook has lost the first round of a court battle against a group of users who sued the company for allegedly storing their biometric data “unlawfully.”

California District Judge James Donato denied Facebook's request to dismiss the case, and it is set to continue.

Biometric data is information about your physical characteristics, and it’s commonly used by tech companies as a form of identification. For example, many smartphones use biometrics to verify users' identities through fingerprint scanners.

As Reuters reports, the plaintiffs in the latest Facebook case allege the company broke the law by collecting and storing this type of data from photographs of their faces.

They claim that Facebook didn't obtain their proper consent to store facial data, which is used to identify users in pictures so they can be 'tagged' more easily by their friends.

The 'tag suggestions' feature is available in the US, but was axed in the EU in 2012 after privacy regulators raised objections.

The plaintiffs claim that Facebook's data storage practices break Illinois' 2008 Biometric Information Privacy Act (BIPA), which requires companies to get consent from customers before collecting and keeping this data.

Facebook argued for the case to be thrown out, claiming the plaintiffs had agreed for their legal dealings with the company to be governed by California law when they signed up to Facebook's user agreement. It also claimed BIPA does not apply to the ‘tag suggestions’ feature.

However, the court ruled that Illinois law still applies, and said the BIPA claim can go ahead.

Writing in his ruling, Donato said: “The Court accepts as true plaintiffs' allegations that Facebook's face recognition technology involves a scan of face geometry that was done without plaintiffs' consent.”

As USA Today reports, Shawn Williams, one of the lawyers representing the plaintiffs, said they were “pleased with the court's well-reasoned decision.”