It can, but it does not do so automatically. A waiver of the rights protected by Article 31 of the Uniform Code of Military Justice (UCMJ), codified at 10 U.S.C. section 831, must be voluntary, knowing, and intelligent. Mental illness is relevant to whether that standard was met, because a condition that prevents a suspect from understanding his rights or from making a free and rational choice can render a waiver invalid. But the mere existence of a diagnosed mental illness, without more, does not by itself defeat a waiver. Courts examine the suspect’s actual mental condition at the time of the waiver under the totality of the circumstances.
What a valid waiver requires
After a proper Article 31(b) advisement, a suspect may choose to waive his rights and speak. For that waiver to be effective, it must be voluntary in the sense that it was the product of a free and unconstrained choice and not the result of coercion, and it must be knowing and intelligent in the sense that the suspect understood both the nature of the rights and the consequences of giving them up. Military Rule of Evidence 305 governs the warning and waiver of rights, and Military Rule of Evidence 304 governs the admissibility and voluntariness of confessions. Mental illness can bear on either prong: whether the choice was truly free, and whether the suspect comprehended what he was surrendering.
The two halves of the analysis
A useful way to see how mental illness fits is to separate the voluntariness inquiry from the comprehension inquiry. Voluntariness focuses on whether the suspect’s will was overborne. As a constitutional matter, this prong generally requires some form of official coercion or overreaching; a confession is not rendered involuntary by a defendant’s mental condition alone where there was no coercive police conduct. The comprehension half asks a different question: did the suspect have the capacity to understand the rights and the consequences of waiving them? Even absent any coercion, a suspect so impaired that he could not grasp his rights may not have knowingly and intelligently waived them.
Why a diagnosis alone is not decisive
Mental illness covers an enormous range, from conditions that have little effect on a person’s understanding to severe impairments that distort perception and reasoning. A service member can carry a psychiatric diagnosis and still fully understand that he has the right to remain silent, the …