Written by Dr. Nicole M. Vienna

April 22, 2022

Consultation with a Lawyer

Forensic psychologists play an essential role in the court systems. They aim to inform and educate the trier of fact. Once qualified in court, forensic psychologists serve in the role of expert witnesses. Often, these professionals are retained to consult, write a forensic report, or provide oral testimony or deposition. Sometimes, the forensic psychologist is asked to conduct an evaluation and render a report. In some cases, that report can lead to oral testimony. Still, the attorney may just want general feedback and consultation regarding the mental health matters at hand. Regardless, in all three categories, the forensic psychologist must base their professional opinions on multiple data points and sources of information, or what attorneys may refer to as “evidence.” This is a best practice in forensic work because individuals in legal contexts have an incentive to distort information. Similarly, one single source of information could offer a biased opinion. Therefore, it is best to use multiple sources of information to base the professional opinion.

Five common sources of information or “evidence” forensic psychologists use to base their professional opinions on are described below.

  1. Records. Historical information helps establish the etiology of problems, symptoms, and impairments. Finding this kind of information in various records can serve to support self-reports by the individuals being evaluated or not. Documents like school records often have multiple people giving accounts of the individual and contain multiple data sets. Other types of records that are often helpful in forensic evaluations (but may vary by type of evaluation) are medical, psychiatric, child welfare, prior forensic evaluations, employment, police reports, and other legal records. It is most helpful if the attorney starts to request the records as soon as possible. It is a best practice for forensic psychologists to review records prior to their evaluations or testimony. It helps adequately prepare the expert for proper test selection and guides the interview.
  2. Clinical Interview. The clinical interview is a source of valuable information that includes behavioral observations and direct reports by the person being assessed during the evaluation. Essentially, it is a data-gathering process needed to diagnose (if required) and answer the psycho-legal question. There are various kinds of interviews, including standardized interviews (a structured interview process where answers can be scored and normed- i.e., C.A.P.S. 5), structured interviews (questions that follow a predictable structure), and spontaneous interviews (questions based upon the answers to previous questions). Still, the expert may employ a combination of some sort.
  3. Collateral Interviews. A primary reason for conducting a collateral interview is to obtain third-party information to verify information reported by the person being evaluated or to gather additional information. Collateral interviews are often conducted with a person’s family members, therapists, other medical providers, co-workers, social workers, caregivers, or any other point of contact that the individual being evaluated may provide. The collateral contact can also include the referral source (attorney or court). These individuals often provide information such as birth and developmental history, psychiatric and medical history, and information about family dynamics and relationships. It is important to note that when interviewing family, friends, and even the treating providers, these individuals can be biased and provide selective information. In some instances, collateral sources may feel shameful or reluctant to share what they perceive as negative information. Skilled forensic psychologists can assist collateral sources by encouraging them to stick to the facts and their observations.
  4. Psychological Testing. Forensic psychologists use testing when indicated or necessary. Specifically, they use standardized tests and assessment tools (i.e., checklists and questionnaires) to measure a person’s behavior, cognitive abilities, academic skills, and emotional functioning. Tests can be administered orally, in paper-pencil style, and even with an assistive device. Since COVID-19, more tests are becoming available to be administered via an online format. However, the psychologist should be cautious and check the validity and reliability of the online format. Nonetheless, the data from the tests help inform diagnosis, range of impairment, overall strengths and weaknesses, and information related to legal capacities.
  5. Specialized Forensic Testing. Forensic psychologists use specialized measures when indicated in assessing response style, yet another important data point in forensic evaluations. These measures are designed to assess defensiveness, effort, test engagement, and malingering. It is important that forensic psychologists select a measure that is well-validated and generally accepted within the professional psychological community. That is, measures and tests must meet the Daubert or Frye standard (depending on the jurisdiction of the case). This is because the judge or trier of fact will use this standard to assess whether the forensic psychologist and their work product (i.e., the report or oral testimony) is based on scientifically valid reasoning and whether that data can be applied to the case at hand. This also applies to the selection of psychological tests.

In sum, forensic psychologists seek to assist the trier of fact or attorney in understanding mental health or psychological issues at hand in a legal case. Accordingly, they provide professional opinions that include interpreting psychological information relevant to the legal issue, whether it be through consultation, evaluations, reports, or expert testimony. To that end, it is a best practice in the field to base professional opinions on multiple sources of information or “evidence.” Such sources include but are not limited to the review of records, clinical interviews, collateral interviews, psychological testing, and specialized forensic testing. Notably, the forensic psychologist must be able to integrate data that may be inconsistent and give appropriate weight to the various sources and come to a sound clinical decision. A must-read detailed discussion on general best practices can be found in the Specialty Guidelines for Forensic Psychology.

Vienna Psychological Group provides forensic evaluations and serves as an expert witness for criminal cases. We follow the above standards to draft our professional opinions. Call our office at (626) 709-3494 or use our online platform to schedule a consultation.


Brannick, Meghan E., “Guidelines for Forensic Report Writing: Helping Trainees Understand Common Pitfalls to Improve Reports” (2015). Graduate School of Professional Psychology: Doctoral Papers and Masters Projects. 63. https://digitalcommons.du.edu/capstone_masters/63

How to get started as an Expert Witness. White Paper by By James J. Mangraviti, Jr., Esq., Nadine Nasser Donovan.

Heilbrun, Kirk., Grisso, Thomas., & Goldstein, Alan M. (2009). Foundations of Forensic Mental Health Assessment. Oxford University Press.

A.P.A. Specialty Guidelines for Forensic Psychology. American Psychological Association. 2013.

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