Key Points

  • Under Iowa Code section 147.139, a health care provider's field is defined by the provider's license, not by a specialty or area of practice within that license.
  • Fields are substantially similar when a practitioner licensed in one would, by that license alone, have the foundational knowledge and competence to opine on the standard of care in the other.
  • Physicians licensed under chapter 148 and physician assistants licensed under chapter 148C practice in substantially similar fields for purposes of section 147.139(1) and (2).
  • A board-certified surgeon was therefore qualified to sign the certificate of merit in a suit against a physician assistant practicing family medicine, and the court reversed the dismissal.
  • The court held that Davenport preserved his statutory-interpretation argument because his appellate arguments added support to a position he took in the district court.

The Iowa Supreme Court ruled Friday that a physician may serve as the qualifying expert in a malpractice suit against a physician assistant, holding that the two professions practice in "substantially similar fields" under the state's law setting minimum qualifications for medical experts.

The unanimous decision, written by Justice Oxley, revived a negligence suit by Joshua Davenport, who alleged that physician assistant Nathanael K. Fuller mistook acute diverticulitis for an enlarged prostate. A Dallas County judge had dismissed the case after ruling that Davenport's expert, a board-certified surgeon, worked in too different a field to support the claim. Chief Justice Christensen did not participate.

The ruling builds on Jones v. Lindell, a 2026 decision in which the court held that a health care provider's "field" under Iowa Code section 147.139 is defined by the provider's license, not by a specialty or practice area. Jones left open how courts should decide whether two different licenses cover "substantially similar" fields. Under the test the court adopted Friday, a physician assistant's work in family medicine does not disqualify a physician expert who practices surgery.

According to the opinion, Davenport saw Fuller, his primary care provider, twice in three days in March 2023 for abdominal pain and trouble urinating. Fuller diagnosed urinary retention caused by a probable enlarged prostate, prescribed medication and then referred Davenport to a urologist. Days later Davenport sought emergency care. He had acute diverticulitis and suffered a perforated bowel, feculent peritonitis and septic shock, and he spent several weeks in the hospital.

Davenport sued Fuller for negligence and served a certificate of merit affidavit, a requirement the Iowa General Assembly added in 2017. Dr. Cass Franklin, a surgeon licensed in Iowa and board-certified in surgery, signed it. Davenport also designated Franklin as his only trial expert.

After Davenport's deadline to name additional experts passed, Fuller moved to dismiss, arguing that a surgeon was not qualified to opine on care by a family-medicine physician assistant. Judge Charles C. Sinnard agreed, writing before Jones was decided that "[a] general surgeon does not practice in the same or substantially similar field as a family practice physician's assistant to the degree necessary to render an expert opinion on the standard of care."

Before 2017, Iowa courts asked whether an expert's qualifications "relate[d] directly to the medical problem or problems at issue," a standard the Supreme Court described as case-by-case. The 2017 law instead requires that the expert be "licensed to practice in the same or a substantially similar field as the defendant."

In Jones, the court held that a urologist and an obstetrician-gynecologist practiced in the same field because both were licensed physicians. It affirmed dismissal there because their board-certified specialties were not substantially similar.

Justice Oxley wrote that the Dallas County court erred by comparing Franklin's and Fuller's areas of practice. "We reiterate what we said in Jones—a health care provider's field is coterminous with his license, not a specific area of practice within that license," the opinion said. Fuller holds a physician assistant license under chapter 148C of the Iowa Code, and Franklin holds a physician license under chapter 148. Because the licenses differ, the court asked whether the two fields were substantially similar.

The court adapted the test Jones had used for specialties. Fields are substantially similar, Oxley wrote, when they "share a high degree of likeness in their core characteristics" and a practitioner in one would, "by virtue of that license alone, possess the foundational knowledge and competence to evaluate and opine on the standard of care applicable to the other field." The particular problems and treatments in a given case play no part in that inquiry, the court said.

Iowa law defines a physician assistant as a person "licensed to practice medicine by the board," the opinion noted, and it excludes nurses, dentists, pharmacists and several other providers from the practice of medicine. "The only section 147.136A(1)(a) providers left as practitioners of medicine are physicians, osteopathic physicians, and physician assistants," the court wrote.

Under state rules, physician assistants may diagnose and treat medical problems and prescribe medication, though they may only assist physicians in surgery and obstetrical care. "Aside from specific areas of practice, such as surgery and obstetrics, physician assistants are licensed to independently provide medical services much like a physician," Oxley wrote.

In Jones, separate certifying boards had weighed against similarity. In this case, the court noted that the board of physician assistants must consult the board of medicine before adopting licensure rules and must include a medical doctor and an osteopathic physician among its members. Those links show "the two boards are not entirely independent, thus distinguishing their relationship from the distinct certifying boards we considered in Jones," the court wrote.

"Lest we define 'a substantially similar' field so tightly as to render it superfluous with 'the same' field, we hold that physicians and physician assistants are licensed to practice in substantially similar fields for purposes of section 147.139(1) and (2)," the court wrote.

Fuller had argued that the legislature did not intend physician assistants to qualify as experts against physicians, a result he said treating the fields as similar would invite. The court disagreed, citing a separate provision of the statute that "requires experts against licensed-physician defendants to also be licensed physicians."

The court also held that Davenport had preserved his argument about the meaning of "field" for appeal, because his appellate briefing was "additional ammunition for the same argument" he made in the district court.

David L. Brown of Hansen, McClintock & Riley argued for Davenport. Jeffery R. Kappelman of Finley Law Firm argued for Fuller.

"Davenport timely served a certificate of merit affidavit signed by a qualified expert, and dismissal of his lawsuit was improper," the court concluded. It reversed the judgment and sent the case back to the Dallas County district court for further proceedings.