Some psychological tests used in court are unscientific

You may have heard of the Minnesota Multiphasic Personality Inventory, or MMPI. This is a standardized test that is routinely used to help determine if someone is suffering from a diagnosable psychological problem. First developed in the 1940s, the test is widely considered to be scientifically valid.

On the other end of the spectrum, you might think about the kinds of personality tests you find on Facebook. They’re generally not developed by psychologists and have no scientific underpinnings.

Which ones should we be using in court?

If you said you’d prefer to see the scientifically valid test used in court, you’re right. By law, courts are only supposed to allow scientific and technical evidence that is 1) widely accepted within the field and 2) backed up by science — not pseudoscience.

Yet, according to a study earlier this year, courts often don’t filter out psychological tests that lack sufficient scientific underpinnings and wide acceptance in the field. That is unfortunate, because the results of a courtroom psychological test could affect the outcome of a criminal or family law case.

From the MMPI to the Rorschach and beyond

For the study, researchers pored over 876 court cases that took place in the United States between 2016 and 2018. The most commonly used psychological test in those cases was the MMPI, which is good news.

Not such good news, the second most common psychological test being admitted into evidence in those cases was the Rorschach “ink blot” test, which is widely considered dangerously ambiguous and subjective, according to the researchers.

Indeed, the researchers found hundreds of different psychological tests being used in courtrooms across the U.S. Of those, a third had never been reviewed in the field’s leading manuals, meaning that they probably are not widely accepted in their field. Of those that had been reviewed in the manuals, only 40% ended up being reviewed favorably. Almost a quarter were deemed by the manuals to be unreliable as evidence.

Unfortunately, lawyers only challenged the validity of a psychological test in less than 3% of all the cases.

Lawyers are supposed to help the courts weed out junk science and keep it from being admitted as evidence. Courts are responsible for ensuring that any evidence used to convict someone is scientifically valid. But this isn’t happening, the researchers concluded.

A Stanford University law professor who was not involved in the study told the Associated Press that he commonly receives unsolicited advertising catalogs for new psychological tests. Those brochures used to tout the scientific validity of the tests they were advertising, but “by the end of the 1990s those numbers had disappeared.”

If a psychological test could be used in your case, it’s crucial you work with an attorney who has the experience and background to challenge the validity of that test, if necessary, or to contextualize the results.