Court Rules Against Forced Fingerprint Unlock

John Lister's picture

A judge says police can't force a suspect to unlock a phone with a fingerprint or other biometric measure, including a suspect's face. It's the latest step in the way privacy laws interact with technological changes.

This ruling came from a federal judge in a court in California and involved a review of a search warrant request. The case involved two suspects allegedly using Facebook Messenger to trying to extort a victim by threatening to publish an embarrassing video. (Source:

The police wanted permission to not only search a location where they believed they would find the suspects, but to unlock any digital devices they found there.

The judge said that in principle the request to search the premises was acceptable, but rejected it based on the digital device element on two grounds. The first was that the request would cover devices belonging to people who weren't named suspects, which was considered too far-reaching. The judge said it went beyond probable cause and thus breached the fourth amendment.

Fourth And Fifth Amendments Relevant

The second reason was laid out in more detail and involved the devices belonging to the suspects. The judge ruled this part of the request was a violation of the fifth amendment because it would involve the suspects incriminating themselves. (Source:

In this context, incrimination wasn't actually about the contents of the devices themselves or anything the suspects might say. Instead the judge ruled that by using a fingerprint or facial recognition, the suspects would inherently be providing testimony that the device did belong to them. That would be a key part in any case against them if, for example, the threatening messages appeared in the Messenger app on the phone.

The judge said police could resubmit the request if it was restricted to only covering digital devices reasonably believed to belong to the suspects, and would only cover seizing the devices rather than forcing an unlock.

Biometrics Cause Legal Rethinks

The ruling is a new twist on search warrants and digital devices, which have so far concentrated mainly on the fourth amendment. Previous cases have addressed the idea that examining a phone should be treated in the same way as searching a filing cabinet in somebody's home.

Other cases have struggled with the contradictory legal arguments that police have the right to take a suspect's fingerprints, but that unlocking a phone isn't usually allowed without a search warrant - something that's prompted legal debate when it comes to biometric security.

What's Your Opinion?

Was the judge's ruling correct in your opinion? Are there any circumstances where you think forcing somebody to unlock a phone would be appropriate and/or constitutional? Does it make any difference if a phone lock is based on a password or biometric measures?

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russoule's picture

first of all, it was a California judge, so it isn't really a surprise that the decision was made against the police.

as to whether the judge is correct or not, why is it that the police can use fingerprints left on objects within the crime scene to apprehend the criminals, but when the "crime scene" is the device itself, suddenly the police cannot use fingerprints? why?

this is another case that needs to go to the Supreme Court to get an answer. it ha become ridiculous in this country that the judicial branch seems to be trying to "write legislation" instead of deciding who is guilty and who isn't.

ronbh's picture

Thank goodness for the judge standing up for personal rights
The police have more than enough tools at their disposal.

" the request would cover devices belonging to people who weren't named suspects,"
Aquessing to this would effectively let the police take anybodies phone at will and force the person to give them access.

If you have yur freedom protect it for all you are worth or you could end up like Canada.

In the crusade against drinking and driving Canadians (or at lease citizens of ontario) now are required to provide a breathalyzer sample with no reasonable cause required , can be charges with drinking and driving up to two hours after making it home, and the onus is now not that the state prove them guilty , they are now considered guilty and must prove their innocence.

Canadians also do not have the right to privacy on their phones, the state can imprison them if passwords are not revealed.

The erosion of freedom can come in small increments and start off with good intentions but beware of the consequences.

plamonica_3840's picture

The ruling is not should a suspect be forced to hand over a password but that unlocking a device in this way would prove that a suspect had legitimate access to a device.