Before getting into the differences between the evaluations, let's first define what clinical psychology is. Clinical psychology is the application of psychological principles, research, and techniques to the treatment, diagnosis, or assessment of human behavior and functioning. Clinical psychology is very broad and can range from treatment of depression with cognitive-behavioral therapy in an outpatient clinic to assessing a child for ADHD in a school to developing a behavioral plan for an individual with schizophrenia in a psychiatric hospital. Forensic psychology is typically a subfield within clinical psychology (though some forensic experts are researchers and have an experimental psychology background). Forensic psychology is the intersection between psychology and the law. In essence, whenever a legal decision relates to mental health or behavior, there is an opportunity for psychologists to assist the legal system. The psychologists who offer psychological expertise to the courts are forensic psychologists.
Referral Source: Most adults who receive clinical assessments are self-referred (though many are referred by a therapist or physician). In other words, they have decided that a clinical psychological assessment will benefit them and are voluntarily requesting it. Children and adolescents are most often referred by their parents or guardians though a school may also request psychological testing. However, in the case of forensic evaluations, the evaluation is almost always court ordered or referred by a defendant's attorney, a government agency, or business (for fitness for duty or pre-employment evaluations).
Who is the Client? In a clinical psychological evaluation for an adult, the client is typically the person who is being assessed. When it is a child or adolescent being assessed, the client is most often the parent or guardian. In a forensic psychological assessment, the retaining party (often the court, an agency, or the attorney) is the client. In some cases, the person being evaluated may not want to participate but is court ordered to do so. In most forensic evaluations, a report is not even provided directly to the person who is evaluated. Recommendations, opinions, and information are directed toward the referral source, not the person who was evaluated.
Confidentiality: Although there are some limitations to confidentiality in clinical psychology settings, clients of clinical psychologists can generally assume the information they provide will be kept private. Court ordered forensic evaluations have no confidentiality. Any information obtained may be put into a report which is provided to the court. Some courts are known to post forensic psychological evaluations on their court websites. I have seen this on several Arkansas county websites. In such instances, anyone in the world can read anything the defendant may have said during the evaluation. This is one reason #9 below is critical. A competent and ethical psychologist does not provide information beyond what is necessary to answer the referral question because of this lack of confidentiality. For other evaluations which are not court ordered (for example a fitness for duty evaluation), the information contained in the report is provided to the referral source, again limiting confidentiality.
Consent: In clinical settings, adults must provide written consent before undergoing a clinical psychological evaluation. The guardians of children or adolescents must provide this for juvenile clinical cases. However, for court-ordered forensic psychological evaluations, no such consent is required. Because the court has ordered it, the evaluation is conducted, even when the defendant may not fully understand the ramifications of the evaluation. In these situations, other ethical and legal principles become salient but are beyond the scope of this post. These situations are another reason #9 is critical.
Nature of the Relationship: In clinical settings, the psychologist is often in a helping role. The psychologist is there to assist the person being evaluated and will provide recommendations directly to the person being evaluated. Forensic psychological evaluations, however, are often more adversarial in nature. The results, opinions, and recommendations of the evaluation are intended for the court and may harm the case of the individual being evaluated. Although many psychologists in clinical roles see themselves as supportive and closely allied with their patient, the forensic psychologist is more distant. This is to preserve objectivity and minimize bias. Though the forensic opinion may ultimately assist the evaluated individual, the forensic psychologist's role is one of neutrality.
Potential for Malingering: Malingering is the exaggeration or feigning of mental health symptoms for the purpose of an external gain. Though there is a possibility of malingering in any setting, this potential is substantially higher in forensic settings than general clinical settings. A good forensic psychologist maintains a healthy skepticism and always considers the possibility of feigning/exaggeration and assesses for it.
Setting: Clinical psychological evaluations are most often performed in community mental health centers, private practice offices, medical facilities, or other outpatient treatment facilities. Though some forensic psychological evaluations also take place in private offices, they are often performed in jails, prisons, and state hospitals.
Accuracy vs. Perspective: When clinical psychologists treat and assess individuals, the most important element is often what the individual believes. If the individual believes their mother is unloving, that can be a central and important focus of treatment. To a certain extent, it does not matter whether the mother is objectively unloving (and whether her behavior is objectively cold or indifferent may be indeterminable). What is central to the therapy is the fact the client believes it to be true. An individual may frequently appear to embellish or minimize information, and the clinical psychologist may choose to ignore this without causing harm (depending on the situation). However, for the forensic psychologist, what is true trumps what is believed. The forensic psychologist must examine the information provided from as many perspectives as are available, synthesizing data, and utilizing behavioral observations and psychometric testing to provide the most accurate, objective, and impartial opinion possible. If the evaluated person appears to be exaggerating or minimizing symptoms or impairment, this is often critical to the formulation of the forensic opinion.
Focus and Relevance: The forensic psychologist is requested to answer a single (or two or three) specific legal questions. Providing opinions and information which do not answer the legal questions is typically seen as irrelevant and even prejudicial. Readability of the report is reduced and unnecessary information which is harmful, misleading, or biasing may be introduced. For example, during an evaluation of competence to stand trial (which requires present capacities), the defendant's history of trauma, physical appearance, relationship with their parents, and/or substance use history may have absolutely no bearing on the psychologist's opinions. If the defendant's childhood sexual abuse, methamphetamine use, and disgust for their parents had no impact on the opinions, than including this information in a public document serves no probative purpose for the court. This information may, however, skew the perspective of the reader or even make harmful or derrogatory statements about others related to the defendant (e.g., a family member the defendant accuses of rape). Clinical evaluations are often sweeping and broad. They may include many pieces of information which do not answer any specific question. Referral questions may be broadly defined and imprecise.