Answer: an expert witness
Explanation: Expert opinion testimony is an exception to the idea that witnesses should report observations rather than speculations or opinions. Knowledgeable experts such as medical professionals can give opinions within their fields of expertise. An example of expert testimony is a doctor’s opinion about whether another doctor deviated from the standard of care that other doctors observe in similar cases. Another example is an examining or treating physicians’ prognosis of the patient’s future condition. Experts can give opinions only within their fields of expertise—a pediatrician can’t speculate about whether brain surgery was properly performed. Likewise, a medical coder can't speculate about whether the repair of a leg fracture was done correctly, but can indicate whether the code assigned for billing the fracture is supported in the medical record. PF