An expert witness must establish a standard for medical care and give an
opinion on whether the defendant’s conduct met this standard. The standard
must at once be general to all practitioners and specific to the individual
plaintiff’s circumstances. Ideally, it should be supported by uncontroverted
scholarly literature. While it need not prescribe a single course of action, it
must either (for the plaintiff) proscribe the defendant’s conduct or (for the
defense) endorse the defendant’s conduct as an acceptable alternative.
These standards ignore the conflict between actual medical practice and legal
expectations. The courts expect that medicine, as a learned, science- based
discipline, will have articulated standards for practice. While recognizing the art
in medicine, the law assumes that the science of medicine will be sufficiently
formalized that the regions of art will be readily identifiable. Rather than face
the core problem of inadequately defined practice standards, the courts allow
experts to step into this void with standards tailored to serve the desired ends
of the lawyer engaging the expert.