Al Franken.Joe Raedle/Getty ImagesThe FBI wanted Apple to use its special technical expertise to help it break security on the encrypted device.
The news will come as a relief for those who assumed that Face ID had failed in its first public test. Apple claims the new Face ID feature is more accurate and secure than Touch ID, which lets users to unlock the device using a fingerprint.
"While details on the device and its reliance on facial recognition technology are still emerging, I am encouraged by the steps that Apple states it has taken to implement the system responsibly", Franken wrote.
Though not entirely new - several Android smartphones do something similar already - the technology remains novel.
During the Apple Special Event on September 12, CEO Tim Cook said, "Technology infused with humanity could improve people's lives and change the world".
Many forms of surveillance - cellphone location tracking, social media analytics and the CIA's reported ability to remotely activate the microphone on an individual's smart TV - were born of such popular consumer advances.
Now, we don't know whether this happened in reality or not. "The acceptable uses could soften up the terrain for less acceptable uses".
For example, it has previously been reported that many facial recognition systems have a higher rate of error when tested for accuracy in identifying people of color, which may be explained by variety of factors, including a lack of diversity in the faces that were used to train a system.
Fatemeh Khatibloo, an analyst with Forrester Research, said authorities in the USA can not compel you to provide your PIN or passcode.
The iPhone X is not due to go on sale until November, and journalists at the launch at the company's Cupertino, California headquarters were shown Face ID working in controlled circumstances. Instead he was prompted to input a six-digit passcode.
Such caveats have earned the company cautious praise from some privacy experts. The company said all facial information is stored on the device and not in the cloud, and it is protected by a "secure enclave".
Here's how Face ID works: Front-facing cameras and sensors map your face to determine if you are actually the owner of the phone. Of course there will be questions about privacy. The Minnesota Democrat is primarily concerned about the privacy implications of Apple's new feature. How does it distinguish a user's face from a photo or mask?
Also slowing the spread of the technology has been the daunting technical challenges of accurately analyzing faces in anything less than optimal circumstances. This one is around the handsome 5.8-inch display in the iPhone X. Apple is using an edge-to-edge display in the iPhone X but there is a bit of black bezel area on the top of the phone. Opening the device later takes only a brief glance.
It works by projecting infrared dots out onto your face, which feeds information back into an AI computer, to create a model of the face and check it against the owner.
Apple said the iPhone X is the basis for the next decade of smartphone technology. The Supreme Court ruled in 2014 that authorities require a search warrant to seize and attempt to examine a smartphone.
This isn't the first phone to have facial detection as a security method.
Despite major investments in the biometrics field, shoppers outside a Los Angeles Apple store on Tuesday afternoon overwhelmingly said they were squeamish about the idea of facial recognition.