You might've thought enabling Touch ID on your iPhone made it more secure. After all, it's harder to fake your fingerprint than to guess a passcode. But when it comes to the law enforcement searches, your smartphone might've gotten a lot more vulnerable.
According to Forbes, federal law enforcement officers recently served a warrant on a California home which gave them "authorization 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."
Essentially, cops could force everyone in the residence to open their phones. Is this really legal?
Fourth Amendment Concerns
The Fourth Amendment protects people "against unreasonable searches and seizures," and generally requires law enforcement officers to get a warrant before searching someone's home or personal effects. In order for the Fourth Amendment to apply, a person must show that he or she has a "reasonable expectation of privacy" in the place being searched or thing being seized. But courts have consistently found that a person has no expectation of privacy in physical characteristics like fingerprints, and that a police may therefore require that a person give fingerprint samples. So requesting a fingerprint to open a phone likely doesn't violate the Fourth Amendment's reasonableness requirement.
In terms of search warrants, they must be based on probable cause, and "particularly [describe] the place to be searched, and the persons or things to be seized." This has generally been interpreted to mean the warrant must be narrow in scope, but, as Electronic Frontier Foundation staff Andrew Crocker told the Washington Post, a warrant that "extended to include any phone that happens to be on the property, and all of the private data that that entails" could stretch those limits.
Fifth Amendment Concerns
The Fifth Amendment, on the other hand, protects people against self-incrimination and could apply to warrants for biometrics in certain circumstances. In general, courts have not found fingerprints, by themselves, to be self-incrimination because they aren't "testimonial" in the sense that they don't amount to a statement about something. But does that necessarily mean that officers can force you to use your fingerprint to unlock your phone?
Law professor and blogger Orin Kerr looked at three such scenarios and opined that, as long as the officers already know that the phone is yours, the answer is probably yes. At that point your fingerprint would not be telling officers anything they didn't already know, or, as Kerr put it, "No testimonial statement from the person is implied by the act of placing his finger on the reader." But when -- as in the case above that involves a search of a residence with multiple phones and multiple people -- cops don't know which device belongs to whom, being forced to unlock a phone could be testimonial:
It amounts to testimony that says, "yes, this is my phone," or at least, "yes, this phone was set to recognize a part of my body as a means of access." It further says: "I am familiar enough with this phone to know that the fingerprint reader was enabled and which part of me was used by me to program the fingerprint reader."
According to Forbes, the warrant in this case is "unprecedented," but we may see similar warrants as more people use their fingerprints to secure their smartphones. If you've been subject to a similar search, you should contact a criminal defense attorney as soon as possible.