In order to submit an expert opinion in a medical malpractice case, both the expert's qualifications and their testimony must meet certain requirements. These are known as standards of admissibility, which differ state to state and on the federal level. Individual states may employ more rigorous standards of expert opinion admissibility. Generally, the trial court must certify the individual as an expert based on their knowledge, experience, training and education in the field in question. Admissibility of an opinion is based on several factors and will normally be subject to one of two standards. These are known as the Daubert and Frye standards, named for two seminal Supreme Court cases, with different jurisdictions usually adopting one of the two.
The Frye Standard of Expert Admissibility
Between 1923 and 1993, federal judges and 45 states adhered to the Frye standard, also known as the “general acceptance” test. Scientific evidence on which an expert opinion was based had to be ‘generally accepted' by the community in that field. Outlier opinions supported by singular studies or evidence not widely backed by a given scientific community were deemed inadmissible. Courts, “in admitting expert testimony deduced from a well-recognized scientific principle or discovery,” must ensure that “the thing from which the deduction is made [is] sufficiently established to have gained general acceptance in the particular field in which it belongs.” This did not leave room for cases that cite evidence which may be scientifically sound but pertain to a ‘niche' area that may not have the prominence necessary to garner 'general acceptance' in the greater scientific community.
Congress penned the Federal Rules of Evidence in 1973, controlling all federal court evidentiary matters. One rule seemed to be at odds with the commonly held Frye standard. If not at odds, it created ambiguity and left too much room for interpretation, this being rule 702.
"If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.”
The Daubert Standard of Expert Admissibility
A 1992 court case called the Frye standard and rule 702 into question, and established a precedent which would alter the standards of admissibility forever thereafter. Daubert v Merrell Dow Pharmaceuticals saw a number of plaintiffs take on Merrell Dow because their mothers had taken one of their drugs during pregnancy, leaving the plaintiffs with birth defects. Plaintiffs cited various pharmaceutical research linking the drug to their defects, however, the trial court ruled that the evidence did not rise to the level of ‘general acceptance' within the scientific community. The Court of Appeals did not wish to rule on the dispute, and eventually, the Supreme Court decided to hear the case. The justices ruled that 702 made no mention of general acceptance as a requirement for admissibility, and devised a new standard by which evidence would be deemed admissible. Under the Daubert standard, named for the case that prompted the change, evidence would now be subject to the following guidelines:
1. The judge is tasked with “gatekeeping” the evidence submitted in the case, thereby determining if an expert's testimony is proceeding from scientific knowledge; there is no requirement for general acceptance, only that their opinion is logically and scientifically sound
2. The judge must also make a determination of relevance and reliability as to the evidence submitted. They are to ensure that testimony is "relevant to the task at hand,” resting "on a reliable foundation".
3. Rather than using ‘general acceptance' as a qualifier of sound scientific knowledge, evidence will be qualified if it is derived using sound scientific method
4. Rather than a test, the court would look for certain illustrative factors of the scientific method in making this determination. There were:
- Whether the theory or technique employed by the expert is generally accepted in the scientific community;
- Whether it has been subjected to peer-review and publication;
- Whether it can be and has been tested;
- Whether the known or potential rate of error is acceptable; and
- Whether the research was conducted independent of the particular litigation or dependent on an intention to provide the proposed testimony
The Supreme Court amended Rule 702 to codify these structural elements established in Daubert.
Rule 702. Testimony by Experts: If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if:
(1) the testimony is based upon sufficient facts or data
(2) the testimony is the product of reliable principles and methods
(3) the witness has applied the principles and methods reliably to the facts of the case.
In 2011, Rule 702 was again amended to make the language clearer. The rule now reads:
Rule 702. Testimony by Experts: A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:(a) The expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue:
(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) The testimony is based on sufficient facts or data;
(c) The testimony is the product of reliable principles and methods; and
(d) The expert has reliably applied the principles and methods to the facts of the case.