U.S. judge rules Fourth and Fifth Amendments protect against forced biometric smartphone unlock

May 14, 2019, 11:53 am EDT | Chris Burt

U.S. law enforcement cannot obtain a warrant to force an individual to unlock a smartphone with biometrics as doing so would violate both the Fourth and Fifth Amendments of the Constitution, according to the ruling of a district court judge.

Chief U.S. Magistrate Judge Ronald E. Bush issued the decision earlier this month, according to recently unsealed documents discovered by Forbes. Police sought a warrant to force an arrested individual to provide a fingerprint to unlock a Google Pixel 3 XL smartphone seized while they were carrying out a search, with a warrant, of a residence suspected to contain child pornography.

Passwords have previously been ruled protected speech under the Fifth Amendment’s right to avoid self-incrimination, but judges have come down on both sides in decisions about whether the same protections extend to biometrics. A decision by Massachusetts Supreme Judicial Court ruled that passwords are not protected, however, and a federal district court judge in the state ruled in April that federal agents could compel a suspected arms trafficker to unlock his iPhone.

In the Idaho case, Judge Bush ruled not only that compelling the use of fingerprints violated the Fifth, but that that violation also implies a violation of the Fourth Amendment, which protects against unreasonable search and seizure. The judge also noted that while not determinative in the ruling, the connection between the phone and the individual is somewhat tenuous, as multiple phones were found in the residence, and the police did not note whether other people live in the home or were present at the time of the search.

What is determinative, according to Bush, “is that the seizure of the same materials by law enforcement officers ‘differs in a crucial respect’ because ‘the individual against whom the search is directed is not required to aid in the discovery, production, or authentication of incriminating evidence.’”

A California judge made similar arguments in a January decision blocking the compelled use of biometrics to unlock a seized device. The government subsequently obtained warrants to search the phones without the use of biometrics, but also filed a request to vacate the judge’s decision, Forbes reports.