Sunday, January 5, 2014

New evidence of psychopathy test's poor accuracy in court

Risk assessment
Original Article

01/05/2014

By Karen Franklin, Ph.D.

Use of a controversial psychopathy test is skyrocketing in court, even as mounting evidence suggests that the prejudicial instrument is highly inaccurate in adversarial settings.

The latest study, published by six respected researchers in the influential journal Law and Human Behavior, explored the accuracy of the Psychopathy Checklist, or PCL-R, in Sexually Violent Predator cases around the United States.

The findings of poor reliability echo those of other recent studies in the United States, Canada and Europe, potentially heralding more admissibility challenges in court.

Although the PCL-R is used in capital cases, parole hearings and juvenile sentencing, by far its most widespread forensic use in the United States is in Sexually Violent Predator (SVP) cases, where it is primarily invoked by prosecution experts to argue that a person is at high risk for re-offense. Building on previous research, David DeMatteo of Drexel University and colleagues surveyed U.S. case law from 2005-2011 and located 214 cases from 19 states -- with California, Texas and Minnesota accounting for more than half of the total -- that documented use of the PCL-R in such proceedings.

To determine the reliability of the instrument, the researchers examined a subset of 29 cases in which the scores of multiple evaluators were reported. On average, scores reported by prosecution experts were about five points higher than those reported by defense-retained experts. This is a large and statistically significant difference that cannot be explained by chance.

Prosecution experts were far more likely to give scores of 30 or above, the cutoff for presumed psychopathy. Prosecution experts reported scores of 30 or above in almost half of the cases, whereas defense witnesses reported scores that high in less than 10 percent.


9 comments :

Kevin said...

Hmmm...forcing someone to register every so often, charging them a fee when they do, and threatening them with arrest if they fail to do so all to keep their civil rights intact. That sounds an awful lot to me like another class of citizens in this country...

dlc said...

Why hasn't the sex offender community taken this man to court? What he did was slander each and every one of you yet he has not been dragged into court. Unity is the only way to get these laws overturned and the rights restored.

nathan rabalais said...

I wonder the samething with lunsford as well and what his you been doing

dlc said...

To get the rights back and get equal treatment the sex offenders must unite with those who are trying to help them and get the governments attention. Writing those in government has done no good because most sex offenders don't want to stick their necks out any further than they already are. Hiding in the shadows does not help the cause as the law makers steals the rights away. All have to unite, stay clear of legal entanglements, and make their voice heard. Only then will these laws get repealed and found unconstitutional. Only then will the rights be returned. Fight the good fight with those of us who will back you and turn the bright light of reality upon these law makers who steal away rights like a thief in the night.

Sex Offender Issues said...

True. If you don't speak out against injustice, then eventually they will come for your rights. Look at what Hitler did? Fear is a great motivator!

dlc said...

So something must be organized. How do we go about it? How can the sex offenders and their supporters get motivated?

Mark said...

" Eventually you will not be able to buy, sell or trade without being in Big Brother's database." I believe this is NOT an obtuse statement at all.

Matt said...

If you are going to mention that Toole confessed to the crime then you should also mention that he later recanted and also the fact that he falsely confessed to over a hundred murders while in prison. The guy was insane and extremely mentally challenged.

Mark said...

In my legal experience for 18+ years, sex offenders in general are timid, childlike, weak, lack character, many are introverted. I do not write this laughingly either. Many adult rapist types, are so narcissistic and self-absorbed, they have no time to go filing law suits, let alone class actions and that is good new for good ol John Walsh. I can go on, but I think you get the point.