When Can Forensic Psychologists Comment on the Credibility of Criminal Defendants?


  • Roberto Flores de Apodaca Concordia University Irvine
  • Lauren P. Stevens Concordia University Irvine
  • Brendon T. Blake Concordia University Irvine




Commenting on Credibility


Forensic psychological examiners are often confronted with assessments in the guilt phase of criminal cases in which a Defendant denies his/her charged conduct, but the existing evidence clearly contradicts their account. This happens often in cases involving charges of violence, sex offending and or substance abuse (Langton, Barbaree, Harkins, Arenovich, McNamee & Peacock, 2008). What is the proper role of the examiner in such instances?; granting the benefit of the doubt and accepting the Defendant’s account, using the one contained in the differing evidence, or making an independent judgment about which is more likely to be true? Does accepting any version mean the expert is offering an opinion on the Ultimate Issue in the case, and encroaching on the role of the Trier of Fact? The Federal Rules of Evidence (FREE) dictate that judgments about Ultimate Issues belong solely to the Trier of Fact, yet the DSM-5 Manual (APA, 2013) instructs us to consider Malingering in every forensic situation; i.e. is the Defendant being honest about his mental state, and by implication, his/her credibility? Our recommendation is that examiners offer no opinions about which conflicting version in a criminal case is the more credible during the guilt phase, and instead, offer “if, then” assessments about a Defendant’s propensity for violence or sexual offending; i.e. if the charges are true, then s/he poses certain levels of risk going forward, for reasons detailed in the report. Such a stance avoids experts “taking sides” during the guilt phase of a case and allows them to fully inform the adversarial, legal process as it deliberates on possible Plea Bargains or Sentencing decisions. We argue that this impartial approach serves a useful function in legal proceedings while adhering to our Ethical Guidelines (APA, 2010).  

Author Biographies

Roberto Flores de Apodaca, Concordia University Irvine

Professor of Psychology

Lauren P. Stevens, Concordia University Irvine

Psychology Department

Brendon T. Blake, Concordia University Irvine

Psychology Department


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