In order for a medical opinion to be admissible as evidence in civil, criminal and administrative cases, the basis of the opinion must fulfill either the Daubert Criteria or the Frye test, depending on the jurisdiction. The judge of the court rules on the admissibility of the expert opinion. The effect of Daubert has been to limit expert testimony to opinions which are based on a scientific foundation. Daubert specifies that adequate scientific support and method and a known error rate must exist. The testimony of a mental health expert rendering an opinion using criteria which does not meet Daubert standards is weakened by the implication that it is not based on "sound science." In some instances, for example, a mental health expert uses an approach where there are no peer-reviewed studies or methods, such as when psychologists compose their own neuropsychological test batteries. In most cases where an attorney is considering a "Daubert challenge," a contemporaneous and up-to-date literature search is indicated. Also, extensive case law presently exists as to specific issues. Being familiar with the Daubert criteria enhances effectiveness in challenging a mental health expert's opinion, whether on voir dire or cross examination. On direct examination, the strengths of an opinion reached under Daubert criteria become a "teaching moment" for the trier of fact, because it will be founded on the science of mental health assessment.
Undue influence occurs when the testator's freewill and freedom of choice in the disposition of the assets of his or her estate is replaced by the substituted judgment/wishes of another. This can apply to creating a will, codicil to amend a will, trust or other legal instrument.
The medical expert cannot express an opinion about the ultimate question to the trier of fact: how much is the plaintiff's emotional distress (emotional injury) worth in dollars? Yet when the question of these monetary damages is put to a jury, their deliberations are better-served if considered in the context of a Forensic Psychiatrist's knowledgeable findings and testimony.
All psychiatric reports evaluate something, but not always the same thing. For example, eligibility for benefits, or fitness to do a job. To make sense of the report, the reader must determine what is being evaluated and how it is being done
In civil cases where emotional distress is alleged, it often occurs that the plaintiff’s attorney designates the treater as his expert. Usually the argument is that the plaintiff’s own therapist has spent many more hours with the plaintiff than the defense expert and therefore "knows" the plaintiff better. The treater often agrees with this reasoning