The State of Florida
v. George Zimmerman case has definitely captured the attention of our
nation. The case is interesting for many
reasons, but the underlying race issue is arguably the most important one. In addition to the many social issues present,
the use of expert witnesses has been a very influential component of this
case. Of special interest to me was the
testimony of Dr. Vincent di Maio, the nation’s leading forensic pathologist and
expert on gunshot wounds. Dr. di Maio’s
testimony helped to aid the defense in illustrating that Trayvon Martin was on
top of Zimmerman when the latter discharged his firearm, going against the
prosecution’s claims that the roles were reversed. Dr. di Maio also indicated that Zimmerman had
suffered head injuries from repeated blunt force trauma, furthering the
defendant’s claims that he shot Martin in self-defense.
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| Dr. Vincent di Maio testifying during State of Florida v. George Zimmerman |
Dr. di
Maio’s testimony, while highly publicized, is not unusual. Physicians and scientists are often called
upon in legal matters to help analyze and interpret evidence. Their expertise is often so invaluable that
cases come down to the results of their inquiries. The importance of scientific and medical
witnesses has inspired curiosity in me.
What is the history of the use of expert witnesses in common law? Where do scientific and medical expert
witnesses fit into our legal code? Most
importantly, how are these witnesses used in current court proceedings, and
what are the prospects for the future?
The Origin of
Expert Witnesses
The origin
of expert witnesses is in England. Under
English law, the first expert witness was used in a 1782 case involving the
silting up of Wells Harbor in Norfolk.
In that case, renowned civil engineer John Smeaton testified, signifying
the first use of an expert witness’ opinion in common law. In the United States, expert witnesses were
codified into US law in 1975, under the Federal Rule of Evidence (FRE)
702. The FREs represented general rules
passed by congress governing how evidence is presented in both civil and
criminal cases.
Scientific
and medical witnesses have greatly helped to shape the rules governing expert
witnesses. Prior to FRE 702, rules for
admissibility of scientific evidence were established in Frye v. United States (1923). In
Frye, the question at hand concerned
whether scientific evidence in the form of a systolic blood pressure deception
test was admissible in court. The Frye ruling indicated that such evidence
was admissible as long as the test or theory was “generally accepted” among a
meaningful portion of the scientific community.
To prove that something was “generally accepted” parties often put a
number of scientific experts on the stand to verify certain tests or
theories. This rule for establishing the
admissibility of scientific evidence is colloquially known as the Frye Test.
After the
adoption of the FREs in 1975 they along with the Frye Test remained the seminal rules governing scientific expert
witnesses. However, in 1993 a new case
would open those rules up to interpretation and eventual amendment. In Daubert
v. Merrell Dow Pharmaceuticals (1993), two citizens born with birth defects
sued Merrell Dow Pharmaceuticals claiming that Dow’s drug Bendectin caused
their conditions. Both opposing parties
relied upon scientific expert witnesses to prove their claims. A district court ruled that the testimony
from the citizens’ expert was inadmissible because the evidence came from
methodologies, such as in vitro and in vivo studies, that were not
“generally accepted” at the time.
After the
Ninth Circuit Court upheld this decision, the citizens’ took their claim to the
Supreme Court. The citizens’ reasoned
that the Frye Test was no longer the
governing standard for admissibility of scientific evidence as soon as FRE 702
was passed. The court agreed, reasoning
that since FRE 702 made no mention of “general acceptance” that the Frye Test was not to be applied in
discerning the validity of scientific evidence.
The
implications of the Daubert ruling
were significant in amending the rules for the admissibility of scientific
evidence given by experts. No longer was
evidence only judged on its “general acceptance” among the scientific
community. Under Daubert, scientific
evidence can be admissible if it is “relevant to the task at hand” and “rest(s)
on a reliable foundation.” In
determining what makes up a “reliable foundation,” conclusions made from
evidence must be based on sound scientific methodology. Sound scientific methodology rests in using
proper scientific method, including empirical testing of evidence, peer review,
proper controls, and determination of potential error rates. In order to prevent the presentation of
“pseudoscience,” judges are given the power to be the final arbiter of any
submitted scientific evidence. These
guidelines outlined in the Daubert ruling
were eventually added as amendments to FRE 702.
Understanding
the history of expert witnesses allows us to determine how science and medicine
shaped one aspect of the US legal code.
In the next part of this series, I will provide an overview of current
medical and scientific involvement in court proceedings. I will examine not only common case-types in
which physicians testify, but case types in which physicians are directly
involved in. Check back soon!
