Fifth Amendment 2.0: The “Testimonial” Nature of Biometric Features

By Christian Martinez, CLS ’20

“I plead the fifth.” Commonly used in American procedural dramas, this familiar phrase refers to one’s right under the Fifth Amendment not to be compelled in any criminal case to be a witness against oneself.[1]Specifically, the right against self-incrimination prevents the “state from: compelling a defendant to make a testimonial communication to the state that is incriminating.”[2]The Supreme Court has long held that testimonial communications were not limited to oral communications[3]but also includes physical acts that “relate a factual assertion or disclose information.”[4]For example, the act of producing incriminating documents in response to a subpoena is “testimonial” because the very act of producing those documents communicates that the individual knew such documents existed and either possessed or controlled them.[5]Similarly, the act of providing a password or combination to a digital device is also “testimonial” for Fifth Amendment purposes.[6]

Despite this, state and federal courts have held that the compelled use of an individual’s biometric features (e.g. fingerprint) to unlock a digital device is not testimonial and therefore not protected by the Fifth Amendment.[7]However, Magistrate Judge Kandis Westmore of the Northern District of California has recently ruled otherwise.[8]The Government submitted to Judge Westmore warrant applications that included, among other things, a request to compel certain individuals to use their biometric features to unlock digital devices.[9]In denying the application, Judge Westmore held that an individual’s use of biometric features to unlock a digital device is a testimonial communication protected by the Fifth Amendment.[10]Specifically, Judge Westmore reasoned that if an individual could not be compelled to provide a password under the Fifth Amendment, then an individual also could not be compelled to provide a biometric feature to unlock a device because it serves the same function as a password.Furthermore, a successful finger or thumb scan confirms ownership or control over the device and would “expose to the government far more than the most exhaustive search of a house[,]” including medical and financial records (which many smartphone apps provide and protect with biometric features).[11]

Judge Westmore’s decision is a resounding reminder that the law must be quicker to adapt to technological advancements. Under the rule adopted by most courts, there is a meaningful distinction under the Fifth Amendment between using a password to protect your smartphone and using your fingerprint to protect the very same smartphone. The rule has turned what seems like an arbitrary decision for most – whether to use a passcode or biometric feature to secure a digital device – into one with significant privacy ramifications. Worse still, if manufacturers of digital devices opt to remove the password option for securing devices, leaving only the biometric options, this rule would severely limit (if not eliminate) any Fifth Amendment protections as to these devices. As biometrics become increasingly integrated with daily life, it is necessary for courts to avoid the mechanical application of predigital rules to post-digital problems.[12]


[1]U.S. Const. amend. V.

[2]State v. Diamond, 905 N.W.2d 870, 873 (Minn. 2018).

[3]Schmerber v. California, 384 U.S. 757, 763-64 (1966).

[4]Doe v. United States (Doe II), 487 U.S. 201, 209-10 (1988).

[5]U.S. v. Hubbell, 530 U.S. 27, 36 (2000).

[6]In re Grand Jury Subpoena Duces Tecum Dated Mar. 25, 2011, 670 F.3d 1335, 1346 (11th Cir. 2012).

[7]See e.g. In re the Search of [Redacted], 317 F.Supp.3d 523, 535-36 (D.D.C. 2018); In re the Search Warrant Application for [Redacted], 279 F.Supp.3d 800, 807 (N.D. Ill. 2017); State v. Diamond, 905 N.W.2d 870, 875 (2018).

[8]In re Residence in Oakland, California, No. 4-19-70053, 2019 WL 176937, at *3 (N.D. Cal. Jan. 10, 2019).

[9] *1.

[10] *3.

[11] *4.

[12]Riley v. California, 573 U.S. 373, 406-07 (2014).