Should Courts Allow Expert Testimony About Credibility?

There's a longstanding maxim that an expert shouldn't invade the province of the jury in assessing credibility.

But does the maxim always make sense?

What if there are circumstances that ordinary jurors don't have much experience with, such as a witness with a psychological condition leading to self-aggrandizing exaggerations? What about victims of rape or other events who show a wooden affect because of their trauma? What about child witnesses?

Prof. Anne Poulin (Villanova) suggests that the courts should more often permit experts to assist juries in their task of assessing credibility.

Credibility: A Fair Subject for Expert Testimony? (July 2007), Villanova University Legal Working Paper Series. Villanova University School of Law Working Paper Series. Working Paper 77, Florida Law Review ____ (forthcoming 2007). Abstract:

This article explores the ways in which experts can assist the jury to assess the credibility of other witnesses and suggests analytical approaches to such expert testimony. The article argues that the courts should be more receptive to expert testimony bearing on witness credibility and engage in a more nuanced consideration of the role played by proffered expert testimony and how the role of the evidence affects its admissibility. Doing so should lead the courts to embrace the promise of the modern rules of evidence and permit experts to assist juries as they assess credibility.