From Passcodes to Fingerprints: The Fifth Amendment’s Role in Digital Self-Incrimination

Dmitriy Smirnov

February 13, 2025

Firm News

I. Riley’s Foundation

The Supreme Court’s ruling in Riley v. California affirmed that cellphones require heightened privacy protections due to their vast storage of personal data. The decision reinforced Fourth Amendment safeguards by requiring search warrants for cellphone data.

Building on Riley, the D.C. Circuit in United States v. Brown addressed whether compelling biometric unlocks—forcing individuals to unlock their phones with fingerprints—violates the Fifth Amendment. Other cases, including G.A.Q.L. v. State and McKathan v. United States, have further examined whether such acts are testimonial.

II. Compelled Biometric Unlocks as Testimonial Acts

A key issue in Brown was whether using a fingerprint to unlock a phone constitutes a testimonial act. The court ruled that compelled biometric unlocking is testimonial because it implicitly conveys knowledge of the phone’s unlocking method, possession, and control—akin to providing a passcode.

This aligns with In re Grand Jury Subpoena, where compelling a defendant to disclose a password without immunity violated the Fifth Amendment. Similarly, in United States v. Blake, the court required a bypass order because the FBI could not compel passcode disclosure without violating self-incrimination protections.

Unlike physical evidence collection (e.g., fingerprinting or blood draws), biometric unlocking reveals information equivalent to stating a passcode—a well-established testimonial act. This reasoning mirrors G.A.Q.L., where a Florida court ruled that disclosing a passcode forces an individual to “reveal the contents of their mind,” triggering Fifth Amendment protections.

The Eleventh Circuit in McKathan reinforced this principle, holding that revealing a password is testimonial because it requires the defendant to use their mental knowledge. These rulings establish a judicial consensus: compelled passcode disclosure is inherently testimonial and constitutionally protected.

III. The Ineffective Application of the Inevitable Discovery Doctrine

In Brown, the government argued that phone evidence should be admissible under the inevitable discovery doctrine. The court rejected this, finding the FBI’s search warrant relied on information from the unconstitutional biometric unlocking. Because the initial search tainted the warrant, inevitable discovery did not apply.

This ruling underscores the need for law enforcement to establish independent probable cause before obtaining digital evidence. In G.A.Q.L., the Florida court similarly rejected the argument that phone contents were a “foregone conclusion,” as the state failed to specify the exact information it sought. Without such specificity, the state’s argument amounted to a fishing expedition rather than a targeted search.

IV. Future Implications: Facial Recognition & Fifth Amendment Challenges

With biometric authentication evolving, Brown raises concerns about facial recognition as a law enforcement tool. Given the court’s reasoning, compelling facial recognition unlocks may face similar Fifth Amendment scrutiny.

Law enforcement may need to shift toward digital forensic tools rather than compelled biometric compliance. Courts must continue scrutinizing these methods to ensure constitutional safeguards remain intact in an increasingly digital world.

Legal Representation for Digital Privacy, Constitutional Rights, and SEC Matters

If you’re facing legal issues related to digital privacy or self-incrimination, seek experienced counsel. Alejandro Soto, Esq., a seasoned criminal defense attorney, specializes in constitutional law and digital privacy matters.

And, as always, if you receive a Grand Jury Subpoena—or an SEC Wells notice, an SEC subpoena for documents or testimony, a FINRA 8210 request, a FINRA on-the-record (OTR) interview request, or a similar inquiry from a state regulator, such as Florida’s Office of Financial Regulation (OFR), act immediately. Contact Fridman Fels & Soto, PLLC to speak with an experienced defense attorney. Prompt action is critical to protect your rights and ensure an effective response.

Mr. Soto is admitted in Florida and Washington, D.C. As a former Assistant U.S. Attorney for over eleven years, he prosecuted white-collar fraud, securities violations, and international money laundering cases. He also served as Deputy Chief of the Major Crimes Section, supervising and training new prosecutors.

Contact Fridman Fels & Soto, PLLC today to schedule a consultation with Mr. Soto. Protect your rights—act now.