EvidenceProf Blog

Editor: Colin Miller
Univ. of South Carolina School of Law

Tuesday, June 3, 2008

Diminishing Returns?: Double Homicide Case Reveals That Tennessee Does Not Have A Diminished Capacity Defense

The last minute plea deal accepted by Antonio Diaz reveals that Tennessee does not allow the defense of "diminished capacity" and does not allow expert testimony on "capacity" unless a two factor test is satisfied.  The facts of Diaz's case can be found in State v. Idellfonso-Diaz, 2006 WL 3093207 (Tenn.Crim. App. 2006).  Briefly put, in January 2004, the then seventeen-year-old Diaz was a passenger in a pickup truck being driven by Eliseo Quintero, when the two men mistakenly thought that the truck struck Tracy Owen, who had been walking or standing on the side of the road.  Diaz subsequently shot Owen, who was pregnant, several times, causing her death.  The State charged Diaz with the first degree premeditated murder of Owen and the first degree premeditated and felony murders of her unborn child.

Diaz filed written notice of his intent to call a psychiatric expert to testify at trial, and the State filed a motion in limine.  In a hearing on the State's motion, Dr. William Bernet testified that he was a full-time faculty member in the Department of Psychiatry at Vanderbilt University School of Medicine and conducted a pretrial psychiatric evaluation of Diaz.  Dr. Bernet testified, inter alia, that Diaz suffered from post-traumatic stress disorder and dysthymic disorder.  Dr. Bernet, however, also testified, that “I cannot say that [Diaz] totally lacked the capacity [to premeditate]. I am saying, simply, that his capacity was impaired to some extent."  Furthermore, he later acknowledged that he was not concluding that Diaz did not premeditate the crimes but was concluding that all of the factors he had discussed "contribute[d] to this reduced ability to premeditate."

At the close of Dr. Bernet's testimony, the State argued that the jury should not be able to hear his testimony, but the trial court disagreed, leading to the State appealing to the Tennessee Court of Criminal Appeals.  That court noted that under Tennessee precedent:

     -"[D]iminished capacity is not considered a justification or excuse for a crime, but rather an attempt to prove that the defendant, incapable of the requisite intent of the crime charged, is innocent of that crime but most likely guilty of a lesser included offense. Thus, a defendant claiming diminished capacity contemplates full responsibility, but only for the crime actually committed. In other words, 'diminished capacity' is actually a defendant's presentation of expert, psychiatric evidence aimed at negating the requisite culpable mental state...However, 'such evidence should not be proffered as proof of ‘diminished capacity.’ Instead, such evidence should be presented to the trial court as relevant to negate the existence of the culpable mental state required to establish the criminal offense for which the defendant is being tried.'"

In other words, Tennessee allows a "lack of capacity" defense, but it does not allow a "diminished capacity" defense.  Accordingly, experts in Tennessee courts may only render "capacity" testimony when that testimony shows (1) that the defendant “lacked the capacity” to form the culpable mental state and (2) that he lacked the capacity due to a mental disease or defect."  The Tennessee Court of Criminal Appeals noted that Dr. Bernet repeatedly stated that he could not say that Diaz lacked the capacity to form the culpable mental states, and thus found his testimony irrelevant and inadmissible.  The eventual result of this ruling was Diaz deciding to avoid trial and accept a plea deal under which he pleaded guilty to two counts of second degree murder and received two 40-year concurrent sentences.

So, what do readers think?  Should states have "diminished capacity" defenses?  It's a question that hasn't received much ink recently, but that might all change with the impending release of Gus Van Sant's movie, "Milk," about Harvey Milk.  Those familiar with the Milk assassination may recall that defendant Dan White's defense was diminished capacity (the infamous "twinkie defense"), and that he was found guilty of voluntary manslaughter rather than murder, which led to public outrage and California repealing the diminished capacity defense.



| Permalink

TrackBack URL for this entry:


Listed below are links to weblogs that reference Diminishing Returns?: Double Homicide Case Reveals That Tennessee Does Not Have A Diminished Capacity Defense:


Michigan no longer recognizes diminished capacity as a defense. People v. Carpenter, 464 Mich. 223, 627 N.W.2d 276 (2001).

Posted by: Greg Jones | Jun 6, 2008 11:40:41 AM

Post a comment