Objective: Law enforcement officers often encounter alcohol-intoxicated suspects, suggesting that many suspects are presented with the challenge of grasping the meaning and significance of their Miranda rights while intoxicated. Such comprehension is crucial, given that Miranda is intended to minimize the likelihood of coercive interrogations resulting in self-incrimination and protect suspects' constitutional rights. Yet, the effects of alcohol on individuals' ability to understand and appreciate their Miranda rights remain unknown-a gap that the present study sought to address.
Hypotheses: Informed by alcohol myopia theory (AMT), we predicted that intoxicated individuals would demonstrate impaired Miranda comprehension compared to sober individuals and those who believed they were intoxicated (but were in fact not; i.e., placebo participants).
Method: After health screenings, participants completed the Wechsler Abbreviated Scale of Intelligence-Second Edition verbal subtests, rendering a Verbal Comprehension Index (VCI) score. We randomly assigned participants to consume alcohol (n = 51; mean breath alcohol concentration [BrAC] = 0.07%), a placebo condition (n = 44; BrAC = 0.00%), or a sober control condition (n = 41; BrAC = 0.00%). All participants (N = 136) completed the Miranda Rights Comprehension Instruments (MRCI), which measured participants' understanding of the Miranda warnings, recognition of the warnings, appreciation of their rights in interrogation and court settings, and understanding of Miranda-related vocabulary.
Results: We found a significant effect of intoxication condition on participants' understanding of Miranda warnings (η²p = .14) and Miranda-related vocabulary (η²p = .05) when controlling for VCI scores. Specifically, intoxicated participants received lower scores for understanding of warnings compared to sober and placebo participants, and lower scores for understanding of Miranda vocabulary compared to sober participants. Alcohol did not significantly impact Miranda rights recognition or appreciation.
Conclusions: Alcohol intoxication may detrimentally impact some facets of Miranda comprehension. Thus, it is important that law enforcement consider refraining from questioning intoxicated suspects. (PsycInfo Database Record (c) 2022 APA, all rights reserved).