If the cops show up with a search warrant, well, you expect they can search the premises. But showing up with a warrant that says every single person on a certain property has to unlock their fingerprint-reading phones and present them for search, too? That’s… pretty surprising. And yet, it turns out, earlier this year, that’s what happened in California.

What happened, Forbes spotted, is this: the Justice Department wanted a warrant to search a property in California. So far, so good.

But that warrant included language authorizing investigators to “depress the fingerprints and thumbprints of every person who is located at the SUBJECT PREMISES during the execution of the search and who is reasonably believed by law enforcement to be the user of a fingerprint sensor-enabled device that is located at the SUBJECT PREMISES and falls within the scope of the warrant.”

In other words: with that warrant, cops can walk a house or apartment building and demand literally everyone inside immediately use their fingerprints to unlock their phones for inspection. To search the entire contents every single device, whether it belongs to an identified suspect or not, that may exist at the search location.

Experts Forbes consulted found the scope and language of the warrant to be shockingly broad. “They want the ability to get a warrant on the assumption that they will learn more after they have a warrant,” one attorney told Forbes.

Another, from the EFF, told Forbes that usually, “It’s not enough for a government to just say we have a warrant to search this house and therefore this person should unlock their phone. The government needs to say specifically what information they expect to find on the phone, how that relates to criminal activity and I would argue they need to set up a way to access only the information that is relevant to the investigation.”

Someone living at the property in question did confirm to Forbes that the warrant was served, saying that law enforcement, “should have never come to my house,” and that neither they nor any relative of theirs at the address had been accused of participating in any crime.

This is far from the first time that law enforcement has compelled phone-owners to provide their fingerprints for phone-unlocking purposes.

There’s a bit of legal confusion, right now, over how law enforcement can or can’t compel you to unlock your phone. As we reported in May, courts have kind of held it both ways.

In Virginia, in 2014, a court ruled that cops can’t force you to reveal a passcode to your phone. That would be making you say something, and you have the right not to say things.

But, that same court held, fingerprints, body language, and other more body-based, physical things are discrete from things you say, and therefore fingerprints are fair game. That’s in line with a 1966 Supreme Court case Forbes mentions that found self-incrimination protections don’t apply to the use of your body as evidence “when it may be material.”

Since that 2014 ruling, there have been more warrants served on device owners in multiple states — California and Texas, making headlines — compelling them to unlock their phones with their fingerprints.

As Forbes observes, however, not all fingerprint unlock requests are successful — and neither of the requests it mentions were. Most phones require a password for the first unlock after powering back up, so if your battery runs down while you’re arguing with the police, or you turn it off before they ask, they may end up out of luck even if they do compel you to put your thumb on the home key.

Feds Walk Into A Building, Demand Everyone’s Fingerprints To Open Phones [Forbes]

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