The field of psychology is not doing enough to screen out unreliable psychological tests that are being used in the U.S. court system, according to a new study. As a result, courts in North Carolina and elsewhere are allowing junk science to improperly influence juries and judges in criminal trials and other court proceedings.

Researchers from Arizona State University examined 876 U.S. court cases between 2016 and 2018 to determine what types of psychological tests were used. They found that the most frequently used test was the Minnesota Multiphasic Personality Inventory, and the second most frequently used test was the Rorschach inkblot test, which was first developed in 1921. While the former is generally well-regarded in the field, many consider the latter to be too subjective and ambiguous to be fairly implemented.

The study also found that around a third of all tests currently used in the court system have never been reviewed in prominent psychology manuals. Of the reviewed tests, only 40% are well-regarded by psychological professionals, and almost 25% are considered unreliable. The researchers also found that only 3% of psychological tests are challenged in court. Legal professionals are not psychological experts and depend on the field of psychology to properly screen tests that are marketed for use in the court system. According to the authors of the study, this is not being done, which may be causing judges and juries to make the wrong decisions in some criminal court cases.

A defense attorney might be able to prevent certain psychological tests from being used against a defendant in court. For instance, by challenging a test as unreliable, it may be deemed inadmissible, preventing it from improperly influencing the judge or jury. An attorney might also seek to admit tests that are favorable to a defendant, boosting his or her chances of obtaining a positive outcome.