top of page

Law Enforcement’s Use or Abuse of Biometric Passcodes?

By: Andrew Fiedler

The iPhone Model 5S introduced Touch ID, which gave users the ability to use fingerprints to quickly access their smartphone device without having to input a numerical passcode. The feature was widely adopted among users and further evolved with the introduction of the Face ID unlock feature included in iPhone X and later models. A seemingly user-friendly convenience has recently developed into one of the largest constitutional arguments of the twenty-first century.

The biometric unlock feature is a law enforcement legal back door into expediting criminal investigations. The issue of law enforcement agencies using biometric features to unlock electronic devices rests upon determining whether unlocking an electronic device with a fingerprint or someone’s face is testimonial in nature. The relevant portion of the Fifth Amendment of the U.S. Constitution is as follows: “No person…shall be compelled in any criminal case to be a witness against himself . . . .” Two elements are necessary to establish that the Fifth Amendment protects words or actions of a person: (1) the person must be compelled to testify and (2) must bear witness against himself. The analysis that follows assumes that a justifiable subpoena compelling a suspect to produce his electronic device for a search has been provided. Further analysis is needed to determine whether using biometric features to unlock the electronic device may be considered witness against oneself.

The debate around what is considered being “a witness against himself” was characterized in Doe v. United States as the differences between a key to a strongbox containing documents and a combination to a wall safe. In United States v. Hubbel, a man was served with a subpoena to produce eleven categories of documents, and, after Fifth Amendment protest, spent a significant amount of time sorting through documents to respond to the eleven categories requested. The documents contained information that was used in a later lawsuit. The court held that assembling the hundreds of documents was not a mere physical act but an extensive use of the mind that was more like telling the combination to a wall safe and not like being forced to surrender the key to a strongbox. When someone is compelled beyond a mere physical act to make extensive use of the contents of his own mind in responding to a subpoena the individual is being compelled to act in a testimonial way.

Law enforcement’s use of someone’s biometric features to unlock electronic devices is more likely a mere physical act than it is an extensive use of the contents of someone’s mind. Unlike gathering and sorting the documents and relevant correspondence in United States v. Hubbel, a suspect being compelled to use their finger or face to open an electronic device is not having to do more than a physical act.The job of searching the phone and making extensive use of the mind is left to the investigators who still may come across password protected content within the electronic device that the suspect has no legal obligation to provide to investigators. Further, the distinguishing characteristic between producing a combination and a key is that a combination is something that is contained within someone’s mind, while a key is something that is tangible that requires little to no use of someone’s mind to produce. Like a key, the production of a finger or face to open an electronic device does not require the individual to be living.

Some federal district courts have determined that law enforcement cannot use biometric fingerprints to unlock electronic devices unless compelling the suspect under the foregone conclusion doctrine. The foregone conclusion doctrine requires that the government know of the existence of the documents, know the person possessed the documents, and could show that knowledge by testimony of others.  The Norther District of Illinois denied an application for a subpoena because the subpoena broadly granted authority to law enforcement to search people within a building and test their finger prints and faces with electronic devices also discovered in the building.

Despite the limited circumstances where subpoenas have been denied for being too general to access a suspect’s electronic device, many cases are determining that the use of biometric features to unlock electronic devices are not forcing individuals to violate their Fifth Amendment rights by bearing witness against themselves. Ultimately, biometric features used to unlock electronic devices are being more affiliated with a key to unlock a strongbox because it is more likely a physical act than it is an extensive use of the mind.


bottom of page