What is it about?

Sexually Violent Predator civil commitment laws seek to identify those who have committed sexual offenses as a result of a mental disorder, are extremely dangerous, and require forensic hospitalization. Forensic psychologists and psychiatrists must testify that the person has a mental disorder that makes them likely to commit a future violent sexual offense if released from custody. The diagnosis is made to a “reasonable degree of certainty.” The problem is that the term has never been defined. We offer a definition that aligns with legal standards of proof.

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Why is it important?

We examined sexually violent predator civil commitment cases over the 30+ years of the law’s existence in the United States and found that there is no definition of the term “reasonable degree of certainty.” Experts merely recite the term with respect to a diagnosis and their ultimate opinions. This is merely an incantation without meaning. For something as consequential as lifetime civil commitment, the expert should set a higher bar and be able to define the standard.


Defining the reasonable degree threshold in line with a clear and convincing burden of proof offers a balance between community safety and civil liberties. We suggest that aligning an opinion to a clear and convincing standard moves it away from rote recitation to one that requires an analysis.

Erik Fox
California Department of State Hospitals

Read the Original

This page is a summary of: Defining reasonable degree of certainty in sexually violent predator evaluations., Professional Psychology Research and Practice, May 2022, American Psychological Association (APA), DOI: 10.1037/pro0000466.
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