The Arizona Supreme Court ruled that treating physicians who have personal and direct knowledge of the patient in question and who testify as to the standard of care, diagnosis, and treatment for that patient are not considered experts for purposes of the One Expert Rule. Further, the One Expert Rule's purpose is to reduce costs in presenting multiple expert witnesses rather than combating cumulative evidence, which is already addressed by Rule 403 of the Arizona Rules of Evidence.

Background of the Case

Dallas Haught was dirt biking when he fell and suffered a serious cut on his knee. He was treated at Payson Regional Medical Center. Haught returned the following two days to the same facility because his condition was worsening. The treating physician at Payson ordered a C-Reactive Protein (CRP) test, which is a marker for infection that measures inflammation. This treating physician misread the results of the CRP test. Because Haught's condition continued to worsen, he was transported to Scottsdale Shea Medical Center where he was seen and treated by a number of physicians. No one at Scottsdale Shea Medical Center checked or inquired about his CRP results. Haught developed necrotizing fasciitis, which resulted in the surgical removal of all of the skin from his injured leg.

Through a conservator, Ronnie McDaniel, Haught sued the healthcare providers involved in his treatment including his treating doctors. Haught claimed that the failure of these parties to properly assess his CRP test results caused his condition to deteriorate which led to permanent injuries and disfigurement. At trial, several of Haught's treating physicians testified as to Haught's treatment and the standard of care utilized in caring for him.

The case went to trial and resulted in a defense verdict. Haught moved for a new trial based on several issues including his claim that, by allowing the testimony of numerous treating physicians, the defense violated the "One Expert Rule." The trial court denied the motion, reasoning that the testimony of the treating doctors diagnosing necrotizing fasciitis and how it is treated was relevant to the doctors' testimony as factual witnesses. The fact that these doctors had knowledge regarding Haught's condition outside of their personal observations and based on their medical education and experience did not designate them as expert witnesses pursuant to the One Expert Rule. Haught appealed.

The court of appeals reversed the trial court and remanded for a new trial. The Court of Appeals found that the treating physicians' testimony was expert testimony as it related to expressing opinions regarding the proper standard of care. After this reversal, the Arizona Supreme Court accepted the case to resolve this recurring issue.

One Expert Rule

In Arizona, expert testimony is generally required to prove negligence in a medical malpractice case. A.R.S. §12-563; Sampson v. Surgery Ctr. of Peoria, LLC, 251 Ariz. 308, 311 (2021). The One Expert Rule has existed in Arizona since 1991. Since then it has undergone several amendments and challenges, but its core principles and purpose remain the same. The current version of the Rule states, "Unless the parties agree, or the court orders otherwise for good cause, each side is presumptively entitled to call only one retained or specifically employed expert to testify on an issue. When there are multiple parties on a side and those parties cannot agree on which expert to call on an issue, the court may designate the expert to be called, or for good cause, allow more than one expert to be called." Arizona Rule of Civil Procedure 26(b)(4)(F)(i) and (ii).

An amendment to the rule states that an "independent expert" is a person who was "not a witness to the facts giving rise to the action." Rule 26(b)(9) cmt. to 1991 amendment. Nothing in the One Expert Rule prevents factual witnesses from offering their opinions on a particular issue so long as that opinion is based on the fact witness's personal observation and knowledge. Therefore, a fact witness who is testifying based on personal observation and action may also offer expert opinion testimony without violating the One Expert Rule.

Here, several of the testifying doctors treated Haught when he was in the hospital. They had personal knowledge, observations and opinions based on these direct interactions with Haught. These doctors were intimately aware of his condition and what occurred in his specific situation, testifying as to facts arising from their treatment of Haught. Their training as doctors also naturally informed their observations and testimony. The court found that their "specific testimony relating to the CRP test and Haught's condition were relevant to their testimony as fact witnesses since it was provided in the context of care and treatment that they provided directly to Haught."

The court concluded that the treating physicians' testimony relating to standard of care, even if it rose to the knowledge level of an expert witness, was permitted because it was based on personal observations and participation in Haught's care while in the hospital. The defense did not violate the One Expert Rule by using their testimony as well as that of an identified and retained expert witness.

Cumulative Testimony

Haught also argued that permitting the treating doctors to testify resulted in cumulative evidence and would set a negative precedent causing "medical malpractice defendants to overwhelm jurors with a deluge of expert opinions and present cumulative testimony on an issue." He argued that the defense presented the testimony of thirteen doctors who were experts on his medical condition, while he was allowed the expert opinion of only one under the One Expert Rule.

The court disagreed with Haught's characterization of the One Expert Rule in this context. The primary purpose of the One Expert Rule is to limit the cost of presenting multiple expert witnesses. "The purpose is to avoid unnecessary costs inherent in the retention of multiple individual expert witnesses." Rule 26(b)(4) cmt. to 1991 amendment.

Arizona Rule of Evidence 403 addresses cumulative evidence. Pursuant to this Rule, relevant evidence can be excluded if its probative value is outweighed by a danger of cumulative evidence. Ariz. R. Evid. 403. The court may prohibit multiple presentations of the same evidence where "it tends to establish a point already proven by other evidence." State v. Kennedy, 122 Ariz. 22, 26 (App. 1979). The court did not find that this rule applied in this case as each physician's testimony related to their personal and direct communications and interactions with Haught, which were each unique in their own right.

With regard to Haught's argument that the defense had more opportunities to present expert testimony by using thirteen treating physicians as witnesses, the court found that argument unpersuasive because any court can allow additional witnesses upon a showing of cause by the requesting party. Haught did not attempt to request additional witnesses or show any cause as to why additional expert opinions were needed to fully present his case.

Important Takeaways

  • Treating physicians who testify as to standard of care, diagnosis and treatment plans who have personal and direct knowledge of the patient in question are not considered experts for purpose of the One Expert Rule.
  • The One Expert Rule is not meant to combat cumulative evidence, but rather its purpose is to reduce costs in presenting multiple expert witnesses.
  • Arizona Rule of Evidence 403 addresses cumulative evidence and relevant evidence can be excluded if its probative value is outweighed by a danger of cumulative evidence. The court did not find that this rule applied in this case.

A party may request additional expert witnesses upon the showing of cause.

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