The Nurse as an Expert Witness

By Elaine Borg
When you are asked to be an expert witness, you testify as to your opinion about some element of the case.

Facts are at the heart of any legal decision. Only once the facts of the matter have been determined by the court1 can a decision be based on the relevant law. It sounds so simple, and yet the complexity becomes apparent when one considers how evidence of facts is put before the court in a case involving medical professionals. Three primary ways of introducing evidence are verbal testimony of the people involved, documents and expert witnesses' opinion evidence.

Unlike a factual witness, an expert witness cannot testify as to what happened during the incident because she was not present. She can testify as to her opinion about some element of the case. In this regard, she is an unusual witness, since in other matters it is the court's opinion that counts.

An expert witness must have some form of specialized knowledge and experience beyond that of the court in order to assist the court in coming to a proper understanding of the evidence. Nurses' and doctors' professional training, skill and experience make them ideal expert witnesses to assist in applying the art and science of their practice to the facts the court must decide.2

A detailed curriculum vitae is commonly used to help establish a health professional's formal qualifications and experience. She should not offer opinion evidence on matters beyond her established expertise. For example, a nurse may be qualified as an expert in emergency nursing in an urban, acute-care teaching hospital, but may not be qualified to give an expert opinion on outpost emergency nursing.

Because an expert witness was not present when the incident occurred, she must have some basis for her opinion. The lawyer or law firm hiring the expert witness will provide materials such as the Statement of Claim, Statements of Defence, transcripts of Examinations for Discovery and a copy of parts of the patient's chart, and ask the expert to form an opinion on a contentious issue in the case. In forming an opinion, an expert witness may make reference to authorities on evidence of best practice at the time of the incident, standards of practice, policy and other relevant materials. The lawyer will decide upon how the opinion is to be reported back to her: verbally, in writing, or both.

If the foundation for the expert's opinion is unreliable, inaccurate or irrelevant, the opinion itself may be found to be useless. For example, a medical malpractice trial was adjourned when a nurse (factual) witness testified that the times she charted on the ICU records were not accurate. The expert's opinions regarding the timing of brain damage were now of no use. The court observed, "It would be unthinkable to ask this court to proceed to hear evidence from five or six medical experts called by the plaintiffs, and a like number from the defendants, all based upon times which, according to the testimony of the nurse, might be proved incorrect. The administration of justice demands better."3

Although most civil trials settle prior to trial, the nurse expert witness may have to testify if there is a trial. Evidence of the expert witness' purported expertise is proffered to the court in a voir dire, a trial within a trial, even though the nurse has previously reported her expert opinion to a lawyer. Alternatively, the court may accept an agreement between the lawyers that the nurse is an expert in her field.

During the voir dire, the court will have to be satisfied about the following four factors in order to hear the expert's opinion evidence:

  1. necessity in assisting the court: Expert opinion evidence is only necessary if it provides information outside the experience and knowledge of a judge or jury;
  2. relevance to a matter at issue;
  3. qualifications; and
  4. the absence of an exclusionary rule of evidence.4

In its Reasons for Judgment, a court typically makes reference to the evidence of an expert witness. For example: "The plaintiff called an expert in nursing care, [Nurse] Joan Tranmer, who for many years has been variously involved in clinical nursing, teaching and research and in her opinion the assessment room strip showed a normal reactive fetus."5

As with any evidence, expert witness opinions may differ. The court has to assess the totality of the evidence and reach a conclusion, as it did in this case:

Nurse Yeomans is required to practice her profession with a reasonable degree of care and nursing skill. The majority of experts called in the field of nursing agree that she did just what was expected of her. Nurse Robinson, called as an expert by the Plaintiff, disagreed...I prefer and accept the opinions of Nurses Michaud and Richardson.6

Nursing and medicine are different disciplines. Expert witnesses in each discipline may lack the qualifications to attest to the other's standards and practices, as in the case where the court said, "[Dr. Fortin, expert witness] made comments on the nursing care, but I shall not include those as he was not qualified [as an expert witness] to give his opinion on the nursing care."7

However, doctors and nurses often work closely together. Their expert witnesses may give opinions that reveal the nature of each other's roles and responsibilities. In this obstetric case, the court had to reach a conclusion as to the roles of the staff nurse and the anesthesia resident. The judge noted similarities in the evidence of one expert nurse and three expert doctors:

I am satisfied that the role of the staff nurse in an obstetrical unit is to monitor the progress of labour including fetal heart rate all the while providing comfort and support to the labouring mother. It is the nurse's role within this unit to collect information particularly with respect to fetal status and to notify other members of the team of significant changes and any problems. This approach was common throughout the evidence of [Nurse] Joan Tranmer as well as Doctors McGrath, Hannah and Yarnell.8

As idealistic as it sounds, our legal system is about fairness in our dealings with each other. Nurse expert witnesses can contribute by providing the court with high-quality evidence so that its judgments are as fair as possible.


  1. Nurse expert witnesses may also testify in legal proceedings other than civil lawsuits, such as professional discipline hearings.
  2. Medical malpractice cases are rife with expert witnesses. In trying to control costs and not detract from the judicial nature of the proceedings, provincial Evidence Acts commonly cap the number of expert witnesses either party can call. For example, The Manitoba Evidence Act, C.C.S.M. c. E150, s.25 states: "Where it is intended by any party to examine as witnesses persons entitled, according to the law or practice, to give opinion evidence, not more than three of such witnesses may be called upon either side without the leave of the court."
  3. Dybongco-Rimando Estate v. Lee, [1999] O.J. No. 1426 (Ont. Gen. Div.) at para 16.
  4. R. v. Mohan, [1994] 2 S.C.R. 9.
  5. Granger (Litigation guardian of) v. Ottawa General Hospital, [1996] O.J. No. 2129 (Ont. Gen. Div.) at para 41.
  6. Sunnucks (Litigation guardian of) v. Tobique Valley Hospital, [1999] N.B.J. No. 344 (Q.B.) at para 165.
  7. Ibid at para 46.
  8. Supra note 5 at para 100.

Note: This article has been reprinted with permission from the Canadian Nurse, June 2004.

This article is for information purposes only and should not be construed as legal advice. In this text, the feminine pronoun includes the masculine and vice versa, except where referring to a participant in a legal proceeding.

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