A person having knowledge or information about a particular subject or event.
Ethical Requirements for Expert Witnesses

Experts should testify only about those aspects of care for which they have direct knowledge, specific educational background, and clinical experienceLimits the likelihood that generalists will provide testimony outside their areas of specialization or expertise
The testimony should be based on a complete review of all the facts of a caseDecreases the chances that the medical record will be misinterpreted as a result of bias or incomplete study
The testimony must be scientifically up-to-date and its conclusions must be verifiable using evidence-based scholarshipPrevents the witness from relying on subjective impressions, ideas, or personal experiences
The payment that the witness receives must not be contingent on securing a victorious outcome at trialLimits the motivation to alter testimony purely for financial gain

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