The U.S. Supreme Court has held that police can search phones with a valid warrant and compel a person in custody to provide physical evidence such as fingerprints without a judge’s permission.

But some legal experts say there should be a higher bar for biometric data because providing a fingerprint to open a digital device gives the state access to a vast trove of personal information and could be a form of self-incrimination.

“It isn’t about fingerprints and the biometric readers,” said Susan Brenner, a law professor at the University of Dayton who studies the nexus of digital technology and criminal law, but rather, “the contents of that phone, much of which will be about her, and a lot of that could be incriminating.”