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Are the psychology tests used in court actually accurate?

On Behalf of | Oct 30, 2020 | Criminal Defense |

Courts are supposed to screen technical and scientific evidence. They are supposed to ensure that this type of evidence is reliable, meaning that it is the product of reliable methods and principles and that the theory behind it is supported by the majority of practitioners in the field.

Generally, when one side introduces technical or scientific evidence, it is up to the other side to challenge it. However, courts are supposed to weed out any junk science, cutting-edge theories and other evidence that may not be reliable.

According to a study released earlier this year, however, that isn’t happening routinely. In both criminal and family law cases, psychological pseudoscience is allowed far too often. This can mean people are convicted, denied custody, denied bail or otherwise given less-favorable treatment.

“There’s huge variability in the psychological tools now being admitted in U.S. courts,” said one of the study’s co-authors, a psychology professor at Arizona State University. “There’s a lot of stuff that looks like it’s junk and should be filtered out by the courts, but it’s not being filtered out.”

The study, which was published in the journal Psychological Science in the Public Interest, concluded that parties challenge the validity of psychological tests less than 3% of the time. Yet questionable psychological evidence was widespread.

The researchers pored over hundreds of psychological tests that had been admitted in recent court cases and found:

  • A third of the tests had never been reviewed in the field’s most prominent manuals
  • Of those that had been reviewed, only 40% were viewed favorably by the field
  • Nearly 25% of the tests were deemed unreliable by the field

The study examined 876 U.S. court cases that took place between 2016 and 2018. The most common psychological test being used in those cases was the Minnesota Multiphasic Personality Inventory, which is generally reviewed positively by the field. That’s good news.

Not such good news? The second most common test in court was the Rorschach “ink blot” test, which was developed in 1921. The ink blot test has supporters, but the majority of psychologists view it as subjective and ambiguous. If challenged by an opposing party, there is a good chance it would be found inadmissible for this reason.

Scientific evidence deserves to be challenged

In 2009, The National Research Council issued a blockbuster report. It claimed that “testimony based on faulty forensic science analyses may have contributed to wrongful convictions of innocent people.” Indeed, the National Registry of Exonerations confirms that DNA has exonerated many people convicted based on scientific evidence.

The fact that something is labeled “science” does not mean it is. It should not mean that judges and juries simply accept the conclusions of the scientific witness. It should not be admitted into evidence without question.

Is a questionable psychological test being used against you in court? It’s time to talk to an experienced defense attorney.