What Is an Expert Witness?

by Lee Soren
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Maybe you’re savvy with digital devices. You can pair a cell phone to a car in record time, and friends always call you first when an error message sends them into a panic. Perhaps you’ve figured out a foolproof way to get your printer to work correctly every time. After all, you are the expert.

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But that doesn’t mean you’ll be called on to testify as an expert witness in the latest computer crimes case. Here’s why.

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What Is an Expert Witness?

An expert witness, by definition, is someone who has extensive education, knowledge and experience in a particular field. These subject matter experts assist the court by providing professional opinions and insights about technical, scientific or other specialized topics. However, to be considered expert testimony, these opinions and insights must be based on proven facts, data or methods of reasoning.

What Qualifications Does an Expert Witness Have?

The qualifications for an expert witness vary depending on the jurisdiction. In federal court, Rule 702 of the Federal Rules of Evidence states that expert witnesses may testify if they possess the following qualifications:

  • Skills
  • Knowledge
  • Training or education
  • Experience

Because an expert’s qualifications are often challenged by the opposing side, their experience and knowledge should be substantive and indisputable. They should also have no history of prior court disqualifications or testimony conflicts.

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What Is Expert Testimony?

Expert testimony is defined as an opinion stated under oath by an expert witness before or during a trial. Expert testimony typically centers around a specialized area, such as ballistics. Although the nature and type of expert testimony can vary depending on whether you’re in a federal or state court, to be admissible in court, these statements must:

  • Be based on facts or data
  • Have conclusions rooted in reliable methods and principles
  • Demonstrate specialized knowledge that can help determine facts or enhance the understanding of evidence

When Might an Expert Witness Testify?

An expert witness may be called to testify during arbitrations, tribunals or litigations. Expert testimony is often used when an expert's knowledge, experience, opinions or insights can establish the facts of a case or help a trial judge or jury better understand the evidence being presented. Lawyers may also use expert witness testimony to evaluate or challenge testimony from the opposing side’s experts.

For example, a court is trying a medical malpractice case, in which a doctor’s actions may have resulted in a patient’s death. Lawyers for the prosecution may use expert testimony from a medical examiner or other medical expert to explain the patient’s condition, treatment or manner of death. These experts may also explain to jurors, in layman’s terms, what certain evidence means and how it applies to the case.

What Types of Professions Do Expert Witnesses Usually Come From?

Expert witnesses often fall into one of the following categories:

  • Medical
  • Financial
  • Scientific
  • Technical
  • Vocational
  • Forensic
  • Engineering
  • Parenting
  • Securities
  • Construction
  • Mental health

However, every court case is different, and experts from countless areas may be called to testify by both the prosecution and defense.

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Can Expert Witnesses Assist With Other Areas of a Trial?

Expert witnesses can do more than testify. Some specialists, referred to as consulting experts, may also be called on pretrial to:

  • Review documents
  • Assess a case’s potential value
  • Formulate a claim or counterclaim
  • Help attorneys mount a defense
  • Help attorneys develop or refine their strategy
  • Identify or calculate damages

Are Expert Witnesses Paid?

Expert witnesses are entitled to payment, including compensation for travel time and mileage. Many experts bill at an hourly rate. However, fees may vary by region, jurisdiction and specialty. An expert witness salary may also be considerably higher in high-profile cases. For example, a construction expert witness in a small civil personal injury suit would typically be paid much less than a neurosurgeon testifying in a high-profile murder trial.

Where Can You Find Expert Witnesses?

Attorneys may find expert witnesses through:

  • Professional associations
  • Prominent universities, research institutes or medical institutions
  • Published literature in a field
  • Referrals from other lawyers
  • Internet searches

To locate experts in unusual, uncommon or hard-to-find niches, it can also be helpful to consult an online expert witness directory. These directories typically maintain lists of individuals who consider themselves experts in a particular field of study.

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