Are forensic experts biased by the side that retained them?
Abstract
How objective are forensic experts when they are retained by one of the opposing sides in an adversarial legal proceeding? Despite long-standing concerns from within the legal system, little is known about whether experts can provide opinions unbiased by the side that retained them. In this experiment, we paid 108 forensic psychologists and psychiatrists to review the same offender case files, but deceived some to believe that they were consulting for the defense and some to believe that they were consulting for the prosecution. Participants scored each offender on two commonly used, well-researched risk-assessment instruments. Those who believed they were working for the prosecution tended to assign higher risk scores to offenders, whereas those who believed they were working for the defense tended to assign lower risk scores to the same offenders; the effect sizes (d) ranged up to 0.85. The results provide strong evidence of an allegiance effect among some forensic experts in adversarial legal proceedings.
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Organizational factors are especially acute in an adversarial legal system, as adversarial allegiance and mindset can cause judgments and conclusions about the same identical evidence to depend on which side retained them.
“Organizational factors are especially acute in an adversarial legal system, as adversarial allegiance and mindset can cause judgments and conclusions (about the same identical evidence) to depend on which side retained them.”
From Biased and biasing: the hidden bias cascade and bias snowball effects (2025) · cites this paper as Murrie et al., 2013
Adversarial allegiance is the tendency to reach conclusions that support the party who hired them.
“Murrie et al. (2013) describe it as the tendency to reach conclusions that support the party who hired them”
From Biased and biasing: the hidden bias cascade and bias snowball effects (2025) · cites this paper as Murrie et al., 2013
Cites
Strengthening Forensic Science in the United States: A Path Forward
Council, N. R. (2009) · CrimRxiv · doi:10.21428/cb6ab371.b2d683d2 · Cited by 1,461 · see citing works
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Curley, L. J., Munro, J., & Dror, I. E. (2022) · Medicine, Science and the Law · doi:10.1177/00258024221080655 · Cited by 80 · see citing works
Recognizing and reducing cognitive bias in clinical and forensic neurology
Satya-Murti, S., & Lockhart, J. (2015) · Neurology Clinical Practice · doi:10.1212/cpj.0000000000000181 · Cited by 42 · see citing works
Biased and biasing: the hidden bias cascade and bias snowball effects
Dror, I. E. (2025) · Behavioral Sciences · doi:10.3390/bs15040490 · Cited by 29 · see citing works
Prosecuting from the bench? Examining sources of <scp>pro‐prosecution</scp> bias in judges
Berryessa, C. M., Dror, I. E., & McCormack, C. J. B. (2023) · Legal and Criminological Psychology · doi:10.1111/lcrp.12226 · Cited by 28 · see citing works
- Authors
- Murrie, D. C., Boccaccini, M. T., Guarnera, L. A., & Rufino, K. A.
- Affiliations
- University of Virginia (US)
- Sam Houston State University (US)
- Venue
- Psychological Science
- Publisher
- SAGE Publications
- Published
- 2013-08-22
- Volume
- 24
- Issue
- 10
- Pages
- 1889-1897
- ISSN
- 0956-7976 (ISSN-L)
- 1467-9280
- OpenAlex
- W2118789792
- Cited by
- 286
- References
- 1
- Citations by year
- 2026: 11 · 2025: 23 · 2024: 19 · 2023: 23 · 2022: 24 · 2021: 26 · 2020: 26 · 2019: 19 · 2018: 21 · 2017: 29 · 2016: 23 · 2015: 17 · 2014: 16 · 2013: 9
- FWCI
- 24.08
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Psychological Science (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Social Sciences › Psychology › Clinical Psychology › Psychopathy, Forensic Psychiatry, Sexual Offending
- Social Sciences › Psychology › Social Psychology › Deception detection and forensic psychology
- Social Sciences › Law › Jury Decision Making Processes
- Keywords
- forensic psychologists, forensic psychiatrists, risk assessment, deception in research
- MeSH terms
- Expert Testimony, Female, Forensic Psychiatry, Humans, Male, Psychology, Sex Offenses, Risk Assessment, Forensic Sciences
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