Emerging Research on Malingered Mental Illness in Criminal Cases
By David Lombard, PhD — Licensed Psychologist, Certified Competency Evaluator (Indiana Division of Mental Health and Addiction), 30+ years in clinical and forensic practice
Few questions come up more often from attorneys than some version of "how do you know the defendant isn't faking it?" It's a fair question, and one the field has spent decades building a research base to answer carefully. I want to walk through what current research actually supports and where it doesn't support the confidence some attorneys expect.
What Malingering Actually Is
Malingering is the intentional production or exaggeration of physical or psychological symptoms, motivated by an external incentive, avoiding prosecution, obtaining a more favorable outcome, or securing some other benefit. Importantly, the DSM-5 does not classify malingering as a mental disorder; it's listed as a condition that may be a focus of clinical attention, defined by the person's motive rather than by any particular symptom pattern. That distinction matters in a courtroom, because it means malingering is a judgment about intent and consistency, not a diagnosis in the way a mental illness is.
How Common Is It, Really?
Research places malingering at roughly 8% to 21% of forensic evaluations generally, with considerably higher rates — up to around 65% — among some populations of incarcerated individuals specifically seeking a psychiatric evaluation. Those numbers can sound alarming out of context, but they cut both ways for attorneys: malingering is common enough in this setting that it must be assessed carefully in every case, and it is also common enough that a well-designed evaluation process, not just clinical intuition, is what the field considers necessary.
Why a Single Screening Question Isn't Enough
One point the research is fairly clear on: brief screening approaches, like simple symptom checklists, have real limits. Studies of common brief malingering screens have found true-positive rates as low as 14% to 20% — meaning most people flagged by a quick screen turn out not to be malingering when examined more closely. This is exactly why competent forensic evaluators don't rely on a single tool or a gut impression, and why an evaluation that does should raise questions for opposing counsel.
The Multi-Method Standard
Current best practice calls for converging evidence from several independent sources rather than any one measure:
Structured interviews specifically designed to detect feigning, most notably the Structured Interview of Reported Symptoms, Second Edition (SIRS-2), considered the field's reference standard for assessing feigned mental illness
Performance validity tests, such as the Test of Memory Malingering (TOMM), which assess whether a person is putting forth genuine effort on cognitive tasks
Broadband personality measures with built-in validity scales, such as the MMPI-2 or MMPI-3, which include specific indices sensitive to symptom exaggeration or inconsistent reporting
Collateral records and history, including whether reported symptoms are consistent with documented psychiatric history predating the legal matter
No single result from any one of these tools is treated as conclusive on its own. It's the pattern across multiple, independent methods that supports a defensible conclusion, and it's this convergence, not any single test score, that should be the focus when reviewing a report.
A Positive Screen Doesn't Cancel a Real Diagnosis
This is a nuance attorneys sometimes miss, and it cuts in a direction that can surprise both sides of a case: a person can have a genuine mental illness and still exaggerate some symptoms, a pattern the literature refers to as partial malingering. A malingering finding doesn't automatically mean a defendant has no legitimate psychiatric condition, and a legitimate diagnosis doesn't rule out some degree of exaggeration. A competent evaluation accounts for this rather than treating the question as strictly all-or-nothing.
What This Means for Case Preparation
For attorneys reviewing any expert's competency or sanity report, a few questions are worth asking directly: Did the evaluator use more than one independent method to assess symptom validity? Is there a specific, standardized instrument, such as the SIRS-2, involved, or only a clinical impression? Does the report address how findings on validity testing were integrated with the ultimate opinion, rather than treated as a separate, disconnected issue? Reports that can answer these clearly tend to hold up considerably better under cross-examination.
If you'd like to discuss how validity testing was handled or should be handled in a specific case, including our Competency & Sanity Evaluations services, I'm glad to talk it through. [Contact / Schedule a Call]
Frequently Asked Questions
Is malingering considered a mental illness under the DSM-5? No. The DSM-5 classifies malingering as a V-code — a condition that may be a focus of clinical attention — rather than a psychiatric disorder. It's defined by an external motive, not by a specific symptom profile.
How common is malingering in criminal forensic evaluations? Research estimates range from roughly 8% to 21% of forensic evaluations generally, with rates reported as high as 65% in some incarcerated populations specifically seeking psychiatric evaluation.
What is the SIRS-2, and why is it used? The Structured Interview of Reported Symptoms, Second Edition, is a structured clinical interview specifically designed to assess feigned psychiatric symptoms, and it's widely regarded as the field's reference standard for this purpose.
Can someone have a real mental illness and still be malingering? Yes. This is known as partial malingering — exaggerating symptoms that are genuinely present but milder than reported. A malingering finding doesn't automatically rule out a legitimate underlying condition.
Should a single test result be enough to conclude someone is malingering? No. Best practice calls for converging results across multiple independent methods — structured interviews, performance validity tests, broadband personality measures, and collateral history — rather than relying on any single tool.
References: