“Making a Murderer” and Brendan Dassey’s Low IQ Defense.

February 21, 2016 - 18 minutes read


The “Netflix docuseries” entitled “Making a Murderer” has generated a lot of interest in Steven Avery’s murder case. Avery’s co-defendant, Brendan Dassey, has been getting some attention, as well, primarily in regard to his low IQ defense. Dassey is Avery’s nephew, who according to his 2013 appellate decision, was tried and convicted of “first-degree intentional homicide, second-degree sexual assault, and mutilation of a corpse.” Tanya Lewis writes in her Business Insider piece, that “[a]s depicted on the show, the conviction appeared to be largely based off of a confession Dassey gave to police, which his defense attorneys argue was coerced . . . [t]he attorneys repeatedly make the case that Dassey was susceptible to police pressure to confess because he had a low IQ.” This first of two posts will look at the nature of what is now called an Intellectual Disorder, and how courts have interpreted testimony of psychologists and psychologists.

Business Insider Piece on the Low IQ Defense.

Ms. Lewis’ interesting Feb. 3, 2016 Business Insider piece is entitled “There’s a big problem with Brendan Dassey’s low IQ defense on ‘Making a Murderer.'”    Tanya Lewis discusses some general theories about Intellectual Disability, (formerly referred to as “mental retardation”). Based upon various writers, she shows that IQ tests measure a fairly narrow slice of intelligence. For example, an IQ test would not, she quotes, show that Dassey would not have understood the consequences of his coercion.

IQ Tests are Generally Part of a Larger Context of Assessment.

Typically however, an IQ test is simply part of a larger “battery” of tests, sometimes given over a period of days. In fact, a California case found violations of federal law where a school district “relied primarily on the IQ test” to determine whether a student would be placed in special education classes.”  {Larry P. By Lucille P. v. Riles, (1984) 793 F.2d 969.}  In order to make an appropriate placement, other information would have included “educational history, adaptive behavior, social and cultural background or health history.” An IQ test was never designed to be the sole indicator of a person’s functioning level.

A Very Brief Discussion of Cognitive Testing.

Diagnostic and Statistical Manual of Mental Disorders

The criteria for a diagnosis of intellectual disorder is found under Neurodevelopmental Disorders in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Addition (the “DSM-5”). It is a classified as a “developmental disability.” Other disorders classified as developmental disabilities include autism, cerebral palsy, and epilepsy. Adults can acquire an intellectual disability, by way of a brain injury or perhaps other causes, but one would not expect relatively flat scores on all the sub-tests that is considered by some to be the hallmark of an intellectual disorder.

Sub-Tests Scores and Verbal and Performance IQs.

An IQ test is composed of subtests, where the sub-test scores are typically grouped under one of two categories, Verbal and Performance. The Verbal and Performance IQ scores are factored together to obtain the Full-Scale IQ or global intelligence functioning, which is the number, typically, to which people refer when talking about, for example, the borderline or average range of cognitive functioning. When the Verbal and Performance scores vary by more than a perhaps ten points, there should be some concern about factors that may impair the reliability of the results. When the discrepancy reaches approximately 25 IQ points, the test results are often found to be invalid. Verbal and Performance score discrepancy can be due to learning disabilities, inattention, brain injury or other factors. It is important to consider that an IQ test is a snapshot of a person’s functioning.

The Verbal Score.

On the WAIS-III, the following are examples of sub-tests that contribute to the Verbal Score: Information (measures general knowledge), Digit Span (measures immediate auditory recall and concentration), Vocabulary, Similarities (subjects comment on the similarity of two otherwise dissimilar items).

The Performance Score.

The following are examples of sub-tests that contribute to the Performance Score: Picture Completion (measures attention to detail), Picture Arrangement (measures ability to determine a logical sequence), Digit Symbol (measures processing speed).

The Typical Range of Full-Scale IQ Scores.

Typically, the low average range of IQ scores would be the range of 80-89. Scores between 71-79 would fall within the “borderline range” of cognitive functioning. Cognition in the low average to borderline range could be anything between an IQ of 71 and 89. There are many other factors, such as a thought disorder, that can depresses the scores.

The DSM’s Discussion of the Need for Clinical Judgment to Interpret the Results.

In the discussion of the Diagnostic Features of an Intellectual Disability in the DSM 5, page 37, it is stated that “IQ test scores are approximations of conceptual functioning but may be insufficient to assess reasoning in real-life situations and mastery of practical tasks. For example, a person with an IQ score above 70 may have such severe adaptive behavior problems in social judgment, social understanding, and other areas of adaptive functioning that the person’s actual functioning is comparable to that of an individuals with a lower IQ score. Thus, clinical judgment is needed in interpreting the results of IQ tests.

There is also, a confidence interval around the IQ score. For example, the IQ ceiling for an Intellectual Disability, an IQ of 70 can be expressed as a confidence band of 65-75, in other words, a person with an IQ of 75 could still be diagnosed with an Intellectual Disability.

Alternative Views of the Ranges of Cognitive Functioning.

I had learned that the borderline range is between 71 and 84, and low average was in the range of 85-95. Last year, in People v. Moore (Wisconsin), these same figures were cited, at footnote 9 which reads as follows:

“An evaluation of the defendant performed at the State’s request determined that the defendant functions in the “borderline” range of intelligence, meaning his intelligence quotient (IQ) score is between 71 and 84. An evaluation of the defendant performed at the defendant’s request similarly concluded that the defendant’s IQ score falls between 69 and 79. Intellectual disability, also known as mental retardation, is commonly defined as an IQ score of 70 or below. See MedLine Plus, U.S. Nat’l Library of Medicine, “Intellectual disability” (last updated May 10, 2013), http://www.nlm.nih.gov/medlineplus/ency/article /001523.htm.”

Brendan Dassey’s Appeal.

Dassey’s own appeal {State v. Dassey, (2013) 346 Wis.2d 278} contained a little background on his disability: “The trial court heard the testimony of Dassey’s mother, his school psychologist and a police interviewer, and had the benefit of listening to the audiotapes and viewing the videotaped interviews . . .[t]he trial court found that Dassey had a “low average to borderline” IQ but was in mostly regular-track high school classes. . .”

Incompetence under Wisconsin Law.

Dassey would have a very difficult case were he to claim incompetence under Wisconsin law. See for example, State v. Meeks, another Wisconsin case where the trial court quoted the definition of competence from Wis. Stat. § 971.13(1), acknowledging that “mental retardation in and of itself is generally insufficient to give rise to a finding of incompetence” but may support such a finding “if the condition is so severe as to render [the defendant] incapable of functioning in critical areas,” and recognized that the State had to prove by “clear and convincing evidence that Meeks was competent as of January 4, 2000.” {State v. Meeks, (2007) 301 Wis.2d 746.}

And as Meeks points out, “whether a defendant is competent is a legal determination for the trial court,” notwithstanding expert opinions to the contrary.

Once the Evidence Is In, it Is Still Subject to Differing Interpretations of the What the Dialogue Between the Defendant and Police Actually Indicated.

In State v. Moore, (2015) 363 Wis.2d 376, Defendant Raheem D. Moore (“Moore”) appealed his conviction of second-degree reckless homicide, as party to a crime. He “pled guilty to the charge after the Milwaukee County Circuit Court denied his motion to suppress certain statements he made during police questioning.” Moore was 15 years of age at time of incident.

The Majority’s Interpretation.

For the majority, “Moore demonstrated that he was able not only to develop a story about his non-involvement in the shooting but also to adapt the details of that story to information—either true or untrue—possessed by the police . . . [f]or example, when detectives suggested that “Jevonte’s” age did not make sense, Moore changed it from between 15 and 16 to between 18 and 19 . . . [w]hen they asked why nobody in the neighborhood knew ‘Jevonte,’ Moore said that those people either did not know him or were lying . . . [w]hen detectives told Moore that he would not have been able to see the flash of the gun from where he claimed to be standing, he changed his supposed position at the crime scene.”

The sum of these interactions, for the court, was that “Moore’s ability to concoct and modify a story ‘on the fly’ suggests a level of sophistication and adaptability perhaps not accounted for by a standard IQ test. Thus, his below-average intellect “does not justify a conclusion that [his] mental condition, by itself and apart from its relation to official coercion, should … dispose of the inquiry into constitutional ‘voluntariness.’ ” (citation omitted). Rather, it must be taken into consideration and weighed against the conduct of police.”

The Dissent’s Interpretation.

But the dissenting opinion, written by Shirley S. Abrahamson, Chief Justice (with whom Justice Ann Walsh Bradley joined), considering the same dialogue, had a significantly different interpretation of Moore’s underlying cognitive abilities, stating in part:

“The defendant did not demonstrate that he understood his right to counsel. At one point, a detective stated as follows: ‘If you decide to answer questions now without a lawyer present, you have the right to stop questioning at any time you wish and the right to ask for and to have a lawyer at any time you wish, including during questioning.’ The detective then asked, ‘What does that mean in your own words?’ The defendant replied by stating: ‘That mean like, if I’m talking to you all, then I don’t want to say no more, I can just, um, don’t say nothing.’”

From this statement, the dissent writes that “[t]he defendant explained his right to stop speaking but did not demonstrate that he understood he could ask for an attorney or have an attorney present at any time (including during questioning). This exchange, which suggests the defendant did not fully grasp his Miranda rights, weighs against the voluntariness of the confession.”


Dassey has an up-hill battle, in part because he is functioning at a level that many place him in the borderline or higher level of cognitive functioning. In State v. Meeks (2007), as quoted above, the court held that “mental retardation in and of itself is generally insufficient to give rise to a finding of incompetence.” But when looks at the entire picture, the results may be different. One thing not mentioned in any of the cases, is the tremendous and unique impact of disabilities occurring during the developmental period (i.e., developmental disabilities), which have a global effect on one’s functioning. Which is why federal law and virtually all states have laws that provide special treatment for persons with developmental disabilities. Perhaps it was subtle, but I do not recall seeing any real consideration of this issue in these cases.

In the next post, I will discuss how the numbers simply represent that point at which a person’s adaptive functioning is two standard deviations below the mean. In fact, California’s definition of the term developmental disability (like many other states) incorporates adaptive functioning as the test of whether a condition represents a severe impairment. See for example, Samantha C.  The next post will also consider other factors that could make the test results unreliable.

Interestingly, the prosecutor who opposed Dassey’s disability defense, found himself on the hot seat and raised a disability defense of his own.

As a Postscript, the Curious Story of Prosecutor Kratz.

Interestingly, Dassey was not the only one in this case to cite emotional difficulties as a basis for leniency. The prosecutor in the case, Kenneth R. Kratz, who opposed Dassey’s defense, found himself the subject of legal investigation and ensuing litigation. His defense included a list of disorders from which he suffered and . . . his role as special prosecutor in the high profile murder trials of Steven Avery and Brendan Dassey in Manitowoc County.

His defense was more successful than Dassey’s, and he was given a four-month suspension, after the Wisconsin Supreme Court found it “was necessary discipline for attorney’s misconduct while serving as county district attorney in sending series of text messages that attempted to persuade domestic abuse crime victim and witness to enter into sexual relationship with him while he was prosecuting the perpetrator of the domestic crime.” There were a host of other allegations, and defenses on the basis of disability, all detailed in the case. Ultimately, the court found that “Attorney Kratz committed the six counts of misconduct described” in the decision.  {In re Disciplinary Proceedings against Kratz, (2014) 353 Wis.2d 696.}