Apple´s newest device, set to go on sale November 3, is designed to be unlocked with a facial scan with a number of privacy safeguards -- as the data will only be stored on the phone and not in any databases.

Unlocking one´s phone with a face scan may offer added convenience and security for iPhone users, according to Apple, which claims its "neural engine" for FaceID cannot be tricked by a photo or hacker.

While other devices have offered facial recognition, Apple is the first to pack the technology allowing for a three-dimensional scan into a hand-held phone.

But despite Apple´s safeguards, privacy activists fear the widespread use of facial recognition would "normalize" the technology and open the door to broader use by law enforcement, marketers or others of a largely unregulated tool.

"Apple has done a number of things well for privacy but it´s not always going to be about the iPhone X," said Jay Stanley, a policy analyst with the American Civil Liberties Union.

"There are real reasons to worry that facial recognition will work its way into our culture and become a surveillance technology that is abused."

A study last year by Georgetown University researchers found nearly half of all Americans in a law enforcement database that includes facial recognition, without their consent.

Civil liberties groups have sued over the FBI´s use of its "next generation" biometric database, which includes facial profiles, claiming it has a high error rate and the potential for tracking innocent people.

"We don´t want police officers having a watch list embedded in their body cameras scanning faces on the sidewalk," said Stanley.

Clare Garvie -- the Georgetown University Law School associate who led the 2016 study on facial recognition databases -- agreed that Apple is taking a responsible approach but others might not.

"My concern is that the public is going to become inured or complacent about this," Garvie said.