Atkins claims: Did Texas psychologist skew data for death?

Denkowski faces loss of license for role in capital appeals

The U.S. Supreme Court's Atkins decision triggered a wave of ferocious legal battles in the 35 death penalty states. Since 2002, an estimated 7 percent of condemned prisoners have filed Atkins claims on the basis of mental retardation, with about 40 percent succeeding. As of mid-2008, by one tally, at least 82 death sentences had been overturned on Atkins grounds.

At the center of these ongoing skirmishes are forensic psychologists, whose expert opinions about a condemned prisoner's IQ and real-world functioning can literally make the difference between life and death.

With so much at stake, the pull toward partisanship is especially strong. In Texas, one psychologist who has testified in a whopping 29 cases -- nearly two-thirds of all Atkins appeals in that state -- now faces the loss of his license for alleged errors that systematically favored prosecutors.

George Denkowski skewed the administration and interpretation of test data to rule out mental retardation, according to an expose by investigative reporter Renée Feltz in the current issue of the Texas Observer. The state Board of Examiners of Psychologists has upheld a complaint against him, finding that he made "administration, scoring and mathematical errors" in three death penalty evaluations. The State Office of Administrative Hearings will hear his case Feb. 16.

The complaint was initiated by Jerome Brown, a forensic psychologist who had worked on opposite sides from Denkowski in five capital cases and was appalled by his technique of inflating obtained IQ and adaptive functioning scores through "estimation."

As Denkowski explained his method in the American Journal of Forensic Psychology, he uses a "composite methodology" to inflate the scores of "persons from the criminal socioculture," on the grounds that formal testing assesses "mainstream skills" that criminal offenders never learn.

In the case of Daniel Plata, a Mexican immigrant featured in the Observer expose, Denkowski used this clinical judgment technique to raise Plata's adaptive-behavior score from 61 to 71, and his IQ score from 70 to 77. (Antonin Llorente, a neuropsychologist who evaluated Plata in his native Spanish, reported Plata's IQ score as 65.)

Click on above image to see excerpt of
Denkowski's videotaped evaluation of Daniel Plata.

This subtly racist argument of cultural deficit seems to be becoming increasingly popular as a way to explain away the deficits of low-functioning Mexican immigrants in particular. I have encountered it in recent cases I have been involved in. Kevin McGrew, director of the Institute for Applied Psychometrics, offers a psychometric critique over at his Intellectual Competence and the Death Penalty blog, focusing on another Texas death case involving a Mexican immigrant.

After hearing all of the evidence in the Plata case, Federal District Court Judge Brock Kent Ellis issued a scathing critique of Denkowski's method, writing that all of his testimony "must be disregarded due to fatal errors." Plata’s sentence was commuted to life in prison.

Plata's lawyer, Kathryn Kase, told the Observer that all 17 appeals in which Denkowski opined against mental retardation should be re-heard:

"When you have junk science in a case, it’s like pouring poison into a punch bowl. You aren’t going to get the poison out. So you have to pour out the punch, clean the bowl, and start all over again."

In the case of one convict, Michael Richard, that suggestion comes too late. Richard has already been executed.

According to the Observer article, Denkowski originally opined that Richard was mentally retarded, with an IQ of 64 and an adaptive-behavior score of 57, well below the 70 cutoff. But he adjusted his scores after prosecutors showed him a list of books found in Richard's cell, concluding that Richard’s reading level suggested he was not retarded.

The defense psychologist, Jerome Brown, said when he asked Richard about these books -- one of which was written in German -- the prisoner said he used the books to sit on, since his death row cell lacked a chair.

Denkowski's unorthodox method has sparked outrage in the psychological community, including two rebuttals in the American Journal of Forensic Psychology (see resources below) and a pointed caution in the 2010 edition of the American Association on Intellectual and Developmental Disabilities’ diagnostic manual against use of his method.

Further resources:

Denkowski, George C. & Denkowski, Kathryn M. (2008). Adaptive behavior assessment of criminal defendants with a mental retardation claim, American Journal of Forensic Psychology, Volume 26, Issue 3, pp. 43-61.

Widaman, Keith F. & Siperstein, Gary N. (2009). Assessing adaptive behavior of criminal defendants in capital cases: A reconsideration, American Journal of Forensic Psychology, Volume 27, Issue 2, pp. 5-32 (response to Denkowski and Denkowski 2008)

Denkowski, George C. & Denkowski, Kathryn M. (2009). Adaptive behavior misconceptions about criminal defendants with a mental retardation claim: A response to Widaman and Siperstein, American Journal of Forensic Psychology, Volume 27, Issue 2, pp. 33-61

Olley, J. Gregory (2009) Challenges in implementing the Atkins decision, American Journal of Forensic Psychology, Volume 27, Issue 2, pp. 63-73 (response to Denkowski and Denkowski 2009)

Blume, John H., Johnson, Sheri Lynn, and Seeds, Christopher (2009), An Empirical Look at Atkins v. Virginia and Its Application in Capital Cases, Tennessee Law Review, Volume 76, p. 625