A federal magistrate judge in California has ruled that law enforcement personnel may not require suspects to unlock their phones with biometric identifiers like a fingerprint, iris scan or facial recognition, saying the practice is unconstitutional.

The decision followed the request for a search warrant in an extortion case. The prosecutors asked for an order to search digital devices in a residence and to require any individuals present in the residence to unlock the devices using their fingers or other biometric information, including iris or facial recognition.

The prosecutors were investigating an extortion case where the targets of the search warrant were allegedly using Facebook Messenger to threaten a victim with releasing an embarrassing video of the victim if the victim did not pay them. The judge held that there were other methods the prosecutors could use to obtain the information that did not violate the Fifth Amendment, including a subpoena to Facebook or with a warrant based on probable cause.

The judge found that there were sufficient facts to support a warrant to search the property, but not to require the residents to unlock their phones and left the door open for the prosecutors to apply for another warrant.