Jurors influenced by crime scene investigation television programs may hold unrealistic expectations about forensic dermatologic evidence, according to a Journal pre-proof published in Clinics in Dermatology, which proposes an expanded definition of the crime scene investigation effect and outlines strategies for dermatologists to minimize its impact in court.

The crime scene investigation (CSI) effect describes unrealistic juror expectations about the speed and accuracy of forensic evidence based on fictional crime programming. First described in 2004 and named after the television program CSI: Crime Scene Investigation, the concept has since been discussed in the legal and forensic science literature. Researchers Philip R. Cohen, MD, of the University of California Davis, and colleagues proposed expanding the definition to include magazines, websites, and social media, which may also shape juror perceptions.

Scope of Forensic Dermatology

Forensic dermatology involves evaluation of the skin, mucosa, hair, and nails to determine cause and manner of death in decedents, as well as assessment of living victims of abuse and neglect, human trafficking, and torture. Manner of death categories include homicide, suicide, accident, natural, and undetermined. The subspecialty is recognized worldwide.

Documented Impact on Jurors

The researchers cited a 2006 survey of 1,027 prospective jurors as a key data source. In that survey, 46% of jurors expected some form of scientific evidence in every criminal case; 22% expected DNA evidence, 32% expected ballistic or firearms laboratory evidence, and 36% expected fingerprint evidence. Expectations varied by crime type—for example, 73% expected DNA evidence in rape cases and 46% in murder or attempted murder cases.

The researchers noted that these expectations may affect courtroom dynamics. Prosecutors may face challenges obtaining convictions when forensic evidence is limited and may feel compelled to present DNA evidence even when eyewitness testimony is available. Defense attorneys may spend additional time educating jurors about the limitations of forensic testing and may call expert witnesses to reinforce those limitations. In some US jurisdictions, attorneys may consider potential jurors’ exposure to crime-related programming during jury selection.

The CSI effect may also influence behavior outside the courtroom. Exposure to crime-related media may prompt some individuals to attempt to avoid detection—for example, by wearing gloves or cleaning crime scenes—contributing to a mismatch between juror expectations and real-world evidence.

Geographic Variation

The researchers noted that the CSI effect appears to be more prominent in the US. Studies conducted in Canada, Australia, and Hong Kong have not demonstrated a similar detrimental effect, with some findings suggesting jurors in those regions evaluate forensic evidence more cautiously.

Dermatology-Specific Areas of Impact

The review identified several dermatologic domains in which unrealistic expectations may arise.

• Tattoos: Tattoos may assist in identifying decedents or suspects, particularly when compared with prior photographic documentation. However, identificationis not always definitive, and databases are not standardized. Jurors may expect rapid or conclusive identification based solely on tattoos, which does not reflect real-world practice.

• Heavy metals: Certain heavy metals—including arsenic, gold, lead, mercury, silver, selenium, and thallium—may deposit in hair and nails and provide evidence of exposure over time. Laboratory confirmation is required, and results are not immediate. External contamination and limited correlation with total body burden may complicate interpretation.

• Skin lesion evaluation: Jurors may expect dermatologists to provide definitive diagnoses for all cutaneous findings or to link lesions directly to specific causes. In practice, many findings are unrelated to cause of death and not all lesions require biopsy.

Real-World vs Television Portrayals

The review emphasized that television depictions differ substantially from real-world forensic practice. Cases depicted on television are often resolved within a single episode, whereas real investigations may take weeks or longer. Television programs frequently depict a single investigator performing multiple roles, whereas responsibilities are divided among specialized professionals in practice, and laboratory timelines are often exaggerated.

Strategies for Minimizing the CSI Effect

The researchers outlined approaches for dermatologists serving as expert witnesses. Juror perceptions of credibility are influenced by factors such as likability, trustworthiness, and expertise.

Recommended strategies include:

• Explaining technical terms and forensic processes in clear, accessible language

• Using visual aids such as charts and photographs

• Providing concise, focused responses

• Acknowledging that media portrayals may differ from real-world practice

• Describing the limitations of forensic evidence

Dermatology-specific guidance includes explaining tattoo interpretation, clarifying methods for detecting heavy metal exposure, and outlining biopsy techniques and tissue processing when relevant.

The researchers also suggested that attorneys consider jurors’ exposure to crime-related media during jury selection and that collaboration among physicians, attorneys, and judges may improve interpretation of dermatologic evidence in court.

Limitations

The review is a narrative overview and does not include original data collection or quantitative synthesis. Evidence supporting the CSI effect varies by geographic region and its impact outside the US may be limited.

The researchers reported no conflicts of interest and no funding for the study.

The study is scheduled to appear in Clinics in Dermatology.