Understanding the broader implications of strategic evidence disclosure in police interviews with suspects

TLDR: In this paper, the authors take an interdisciplinary approach and consider strategic evidence disclosure within the broader legal context of a suspect's custodial detention and find that it impinges upon the suspect's legal rights and is unlikely to make interviewers less guilt-presumptive.

Abstract: Police around the world present evidence to suspects at different points during the interview. Some psychologists suggest that police should strategically delay disclosing evidence and test the truthfulness of a suspect’s account by comparing it with the evidence. Moreover, psychologists suggest interviewers who plan strategic evidence disclosure might be less guilt-presumptive about the suspect because they must consider alternative explanations of the evidence as part of their planning. In contrast, many lawyers argue that police should not strategically disclose evidence as it undermines a suspect’s fair trial rights and prevents lawyers from advising suspects effectively before the interview. To address these conflicting perspectives from the domains of psychology and law, this thesis takes an interdisciplinary approach and considers strategic evidence disclosure within the broader legal context of a suspect’s custodial detention. First, a field study of police disclosure briefings with lawyers, lawyer-client consultations, and police interviews, and a survey of lawyers highlights how lawyers rely upon the police’s evidence to advise suspects in custody. When police strategically disclose evidence, lawyers cannot provide informed legal advice and tend to advise suspects to not answer police questions. Second, three experiments and a mini meta-analysis show that generating alternative evidential explanations for criminal cases, as interviewers planning strategic evidence disclosure might do, has a very small effect, or plausibly no effect, on people’s beliefs about the suspect’s guilt. Finally, a mock crime experiment shows that, even two months after a crime, truthful suspects’ accounts fit evidence that was strategically withheld more than deceptive suspects’ accounts did. Independent laypeople from a follow-up experiment could distinguish between these truthful and deceptive accounts. Together, these findings suggest that strategic evidence disclosure could help deception detection even months after a crime, but it also impinges upon suspects’ legal rights and is unlikely to make interviewers less guilt-presumptive.