Defense neuropsychologists are hell-bent on being able to testify whether they believe an injured person is telling the truth. They cannot be serious, you say. Determining the veracity or credibility of a witness is the exclusive province of the finder of fact. They are serious, and they’ve devoted a lot of time and energy coming up with a "consesus statement" wherein they agree they should be able to provide this testimony. See American Academy of Clinical Neuropsychology Consensus Conference Satement on Neuropsychological Assessment of Effort, Response Bias, and Malingering, The Clinical Neuropsychologist, 23: 1093-1129, 2009.
The crux of the "consensus statement" is that "neuropsychologists are capable and qualified to diagnose malingering," and that this diagosis "can be used to assist the trier-of-fact (e.g., judge, jury) in a legal decision-making process." Id. at 1099. The authors identify the types of people against whom they believe they are likely to offer this testimony. They include people seeking financial compensation for injuries, people seeking to be compensated for time away from work, soldiers injured during combat, and criminal defendants. Id. at 1098. Indeed, defense neuropsychologists have been complicit with the Veterans Administration’s disgraceful efforts to deny benefits to our unfortunate soldiers who’ve suffered brain injuries from blast-induced injuries suffered in Iraq.
These forensic defense neuropsychologists are publishing their own literature and creating their own consensus statement to justify their defense testimony. Rather than get too bogged down fighting them on their own turf, I prefer to stick to long-standing jurisprudence. The neuropsychologists freely admit that they are trying to divine the witness’s intent, and comment on his or her veracity and credibility. One passage from the consensus statement says, "[i]n considering the diagnosis of malingering, the clinician is explicitly making a determination of intent: more specifically, a determination of intentionally exaggerated symptoms and/or diminished capability with the goal of obtaining an external reward." Id. at 1097. In other words, they want to testify that your client is lying by either faking symptoms or feigning an inability to perform a task. Fortunately, most states’ statutory and/or case law provides that a determination of the veracity or credibility of a witness is the sole province of the jury and not the proper subject of expert testimony. See e.g., Pritchett v. Commonwealth, 263 Va. 182, 186-187 (2002), and Brown v. Corbin, 244 Va. 528, 532 (1992)("The issue of a witness’s credibility falls squarely within the jury’s province, and is one which a jury can resolve without any expert testimony to assist it.").