Expert testimony in criminal court cases

Janeen DeMarte

In my quest to find something good on TV for a half hour or so today, I stumbled across the trial of Jodi Arias just in time to see the expert testimony of Janeen DeMarte, a psychologist working for the prosecution. I must admit that she was very impressive in rebutting all the claims from the expert working for the defense, who claimed that Arias suffered from PTSD. DeMarte was articulate, held herself well in the courtroom, and delivered testimony that is potentially devastating to the claims of the defense.

In DeMarte’s assessment of Arias, she speculated that Arias has Borderline Personality Disorder. Borderlines are known for erratic behavior and seem to have poor emotional control. They are also known to have limited affect (emotional range) and struggle with empathy.

At this point in the trial, the court is trying to determine the state of Arias’ mind during the killing, which will of course help to determine the sentence. As the death penalty is not off the table yet, this is clearly a crucial thing to decide. But this made me realize, even more so, that some disorders are associated with violent behavior whereby the aggressor was not in a ‘right state of mind’ and there are some disorders associated with violent behavior whereby the aggressor was in full control.

This means that whenever the state of mental health is called into question during a criminal court case, the behavior of the prosecution and the defense will become predictably formulaic. You have column A disorders and column B disorders. If you want to argue one way, then you have to pick a column B disorder and rebut diagnoses of any column A disorder. Skeptics argue that you can always find a mental health expert to pick the right diagnoses, depending on what side they are on.

This is where the integrity of mental health experts is really called into question, especially when needing to resist a hurried diagnoses. As DeMarte went through the criteria for PTSD, as presented in the DSM IV, I just kept thinking, “Aren’t many health specialists opposed to the DSM? And if so, how is rebutting this criteria useful?” I can see both the usefulness and the problem with the DSM, but other than considering its utility in diagnosing a patient, it’s clearly also a standard that can be used in court. Would a more dynamic approach to mental health ‘categorization’ provide the same standard and gravitas in a court room?

I long for a day where both law and psychology can keep their integrity and be at peace with one another.

7 thoughts on “Expert testimony in criminal court cases

    1. Jack Pemment Post author

      Thank you! I did become a little concerned when I realized that I was enjoying the cross-examination of the psychologist just a little too much!

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  1. Girl for Animal Liberation

    Last Friday 20/20 aired a piece on Jodi Arias. I learned that Jodi had called the police to “assist in the investigation”. I thought that was pretty stupid, unless she wanted to be caught? I don’t know much about the human psyche but the impression I got was that deep down Jodi wanted to get caught. She wanted everyone to know she murdered her ex boyfriend. Of course, naturally my next question is, why? Why do some killers want to get caught? Is it me or did Jodi loooooooooooooove the limelight? The girl scares me. IMHO she is cunning and was clearly aware of what she was doing — perhaps even methodical. She certainly had plenty of time to map out a plan while driving to her Ex’s house, right?

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    1. Jack Pemment Post author

      I think Arias is a narcissist. I think she was trying to both throw suspicion away from herself by assisting the investigation (why would she be trying to help if she was the killer?), but I’m sure she was getting a kick out of this risk taking behavior, too. I don’t think she ever wanted to be locked away, but I’m sure she has enjoyed all of the attention the trial gave her. I’m not sure narcissists really think in the long term; when they’re at their worst, life is all about short term kicks. So, I think she could enjoy the attention without being bothered by thoughts of jail; she has such a high opinion of herself, she probably never thought she would be declared guilty.

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      1. Girl for Animal Liberation

        It was chilling to watch her.

        I give you a lot of credit for trying to understand the inner workings of the human mind. Your blog is chalk full of interesting information… I have spent far too much time on it. Ha-Ha!

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      2. Jack Pemment Post author

        It’s kind of you to say so! One of the most interesting things about human behavior is that the more you try to understand it, the more you realize there will always be unforeseen variables. Humans always throw you a curve-ball. Still, we do what we can.

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