In 2009, the National Research Council issued a report on forensic analysis in court. It found that few forensic investigative techniques are supported by sufficient science.
The Federal Rules of Evidence require judges to admit evidence from expert witnesses, like forensic analysts, only when their testimony is “based on sufficient facts or data” and “the product of reliable principles and methods.” State rules of evidence have different standards. For example, the Iowa Rules of Evidence allow experts to testify whenever their “scientific, technical or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue.”
Regardless of the wording of the rules, however, courts are expected to consider only scientific and technical evidence, not junk science, hunches or mere opinions. But a recent study published in the journal Psychological Science in the Public Interest raises questions about whether that is happening.
“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,” says Tess Neal of Arizona State University, who co-authored the study.
Second most common psychological test in court: The Rorschach Inkblot Test
The researchers pored over 876 U.S. court cases that were filed between 2016 and 2018. In those cases, which included criminal cases, family law cases and others, the most common psychological test was the highly-rated Minnesota Multiphasic Personality Inventory. This test is considered a standard, scientific test for diagnosable psychological conditions and has generally positive reviews in professional literature, according to the study.
The second most commonly used test, however, was the Rorschach test, known as the inkblot test. The test, developed in 1921, is not generally accepted within the scientific community, although it has its defenders. The reason the Rorschach test isn’t generally accepted as scientific is that the results are highly subjective and ambiguous, depending in large part on the opinion of the testing psychologist.
One professor of law and psychology at Stanford University points out that he routinely receives unsolicited brochures about new psychological tests. He notes that the brochures used to contain data about the tests’ effectiveness, but “by the end of the 1990s those numbers had disappeared.”
When the National Research Council released its report in 2009, it called for reform in how judges assess and evaluate scientific evidence. It appears that similar reforms are needed when it comes to the use of psychological testing, but the process for reform is slow.
According to the study, lawyers challenged the admissibility of a psychological test in less than 3% of the cases studied.