Full Opinion

In the Iowa Supreme Court No. 25–1183 Submitted September 9, 2026—Filed October 16, 2026 Joshua Davenport, Appellant, vs. Nathanael K. Fuller, Appellee. Appeal from the Iowa District Court for Dallas County, Charles C. Sinnard, judge. A plaintiff appeals from a district court judgment dismissing his medical malpractice claims for lack of a qualified expert. District court judgment reversed, and case remanded for further proceedings. Oxley, J., delivered the opinion of the court, in which all participating justices joined. Christensen, C.J., took no part in the consideration or decision of the case. David L. Brown (argued) of Hansen, McClintock & Riley, PLLC, Des Moines, and Gregory W. Landry of McCarthy & Hamrock, P.C., West Des Moines, for appellant. Jeffery R. Kappelman (argued), Erik P. Bergeland, and Regan A. France of Finley Law Firm, P.C., Des Moines, for appellee. 2 Oxley, Justice. To make out a prima facie case for medical malpractice, plaintiffs must generally support their claim with an expert qualified to opine about the care provided by the defendant. The general assembly has set minimum requirements for such experts. Previously, an expert qualified if the expert’s “medical . . . qualifications relate[d] directly to the medical problem or problems at issue and the type of treatment administered in the case.” Iowa Code § 147.139 (2016). In 2017, the Iowa General Assembly enacted new qualification standards for medical experts in the same legislation that added the certificate of merit affidavit requirement in Iowa Code section 147.140 (2024). 2017 Iowa Acts ch. 107, §§ 3–4 (codified at Iowa Code §§ 147.139–.140 (2018)). Now, an expert must be licensed to practice in “the same or a substantially similar field as the defendant.” Iowa Code § 147.139(1). We recently addressed the new “same or a substantially similar field” standard in Jones v. Lindell, 32 N.W.3d 445, 451–52 (Iowa 2026) (quoting Iowa Code § 147.139(1) (2023)). There, we concluded that “field” was coterminous with “license” such that the proposed expert and the defendant in that case practiced in the “same” field because they were both licensed physicians. Id. at 451. Here, the plaintiff provided a certificate of merit affidavit signed by a physician with a board certification in general surgery to support a malpractice action against a physician assistant. This case asks us to consider a question not reached by Jones: how to determine whether an expert and defendant practice in “substantially similar” fields—specifically, a physician and a physician assistant. The district court dismissed the suit after determining that a general surgeon practicing in an emergency department did not practice in the same or a substantially similar field as a physician assistant practicing family medicine 3 in an outpatient clinic setting. Notably, we had not yet decided Jones when the district court entered its order. As further explained below, we hold that under the categorical approach we adopted in Jones, physicians do practice in a substantially similar field as physician assistants. We therefore reverse the district court’s dismissal and remand for further proceedings. I. Factual Background and Proceedings. In March 2023, Joshua Davenport saw his primary care provider, physician assistant Nathaneal Fuller, twice in three days, complaining of abdominal pain and trouble urinating. On March 7, P.A. Fuller diagnosed Davenport with urinary retention secondary to a probable enlarged prostate and sent him home with medication. On March 9, P.A. Fuller told Davenport he could double the dosage, and the next day, referred Davenport for a urology consultation. A few days later, Davenport’s symptoms worsened, and he sought emergency care. P.A. Fuller’s diagnosis was proven wrong. Davenport had acute diverticulitis. He suffered a perforated bowel, feculent peritonitis, and septic shock, requiring him to be hospitalized for several weeks. Davenport sued P.A. Fuller for negligence. He alleged that P.A. Fuller’s examination was deficient and that he prescribed a course of treatment that allowed Davenport’s undiagnosed diverticulitis to progress, resulting in serious physical injuries and missed work. Davenport timely served P.A. Fuller with a certificate of merit affidavit signed by Dr. Cass Franklin. Dr. Franklin’s certificate of merit affidavit stated: 1) I am a physician licensed and in good standing in the State of Iowa to practice surgery, including trauma surgery. 2) I am a physician Board Certified in the specialty of surgery. 3) I am educated, experienced, board certified in the specialty of surgery and am familiar with the applicable standard of care for 4 surgery and medical professionals providing care, skill, and learning in surgery, including but not limited to the fundamentals of urgent care and the specialty of emergency medicine and trauma. Davenport also designated Dr. Franklin as his only expert for trial. After Davenport’s deadline to designate additional experts expired, see Iowa Code § 668.11, Fuller moved to dismiss the lawsuit for failure to comply with Iowa’s certificate of merit affidavit requirements. Fuller argued that Dr. Franklin, as a surgeon, was not qualified to opine on the standard of care for a physician assistant practicing as a family medicine or primary care provider. The district court agreed. In its order dismissing the suit, filed before we decided Jones, the court explained 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” and that the respective “fields of practice and the certifications of Dr. Franklin and PA Fuller are distinct enough from each other to render any opinion on the expected standard of care insufficient to base a finding of a breach of that standard.” Davenport appealed, and we retained the case. II. Analysis. The parties dispute whether the district court properly considered Dr. Franklin and P.A. Fuller’s respective areas of practice in general surgery and family medicine in determining whether Dr. Franklin was qualified to sign a certificate of merit affidavit for Davenport as required by section 147.140. Fuller further argues that Davenport failed to preserve the textual arguments included in his brief on appeal to support Dr. Franklin’s qualifications. The dispute turns on issues of statutory interpretation, which we review for correction of errors at law. Jones, 32 N.W.3d at 450. 5 A. Error Preservation. First, we briefly address error preservation. Davenport argues that the district court misinterpreted the meaning of the word “field” in section 147.139. Fuller claims that Davenport is foreclosed from advancing this textual argument on appeal because the district court’s dismissal was not based on statutory interpretation. The purpose of error preservation is to “give[] opposing counsel notice and an opportunity to be heard on the issue and a chance to take proper corrective measures or pursue alternatives in the event of an adverse ruling.” Lee v. State, 815 N.W.2d 731, 739 (Iowa 2012) (emphasis added) (quoting State v. Mann, 602 N.W.2d 785, 790 (Iowa 1999)) (holding that the state’s sovereign immunity argument pressed on appeal was preserved by its more general argument in district court that it was immune from suit in its own court). A party preserves an issue for review by “alert[ing] the court of its essential claim.” Bartlett Grain Co., LP v. Sheeder, 829 N.W.2d 18, 24 n.4 (Iowa 2013). Parties can introduce new legal authorities on appeal so long as they are “additional ammunition” for an argument properly raised below. JBS Swift & Co. v. Ochoa, 888 N.W.2d 887, 893 (Iowa 2016). Davenport’s statutory arguments meet this standard. Fuller raised the issue of Dr. Franklin’s qualifications as an expert in his motion to dismiss, arguing that his licensure, certification, and practice experience as a physician did not satisfy section 147.139(1) and (2). In response, Davenport challenged Fuller’s specialty-based characterization of the relevant fields. He quoted the statute to argue that “Defendant and Cass Franklin, M.D. are licensed to practice in the same or substantially similar fields of medicine.” Describing on appeal how Fuller and the district court diverged from the statutory text in determining 6 whether Dr. Franklin satisfied its requirements is merely “additional ammunition for the same argument.” Id. Ultimately, the meaning of a statute is for the courts to decide, and we are not bound to apply erroneous interpretations provided by the parties. Christensen v. Iowa Dist. Ct., 21 N.W.3d 529, 532 (Iowa 2025). The parties disputed the interpretation of “field” before the district court in arguing about whether Dr. Franklin was qualified to serve as an expert under section 147.139(1) and (2), and we properly consider the statute’s meaning on appeal. See Ames 2304, LLC v. City of Ames, 924 N.W.2d 863, 868 (Iowa 2019) (holding that error was preserved on statutory-interpretation arguments over the meaning of the word “intensity” where the parties disputed whether a remodel of property would increase the intensity of a nonconforming use). B. Expert Qualifications for a Certificate of Merit Affidavit. Turning to the merits, we begin with an overview of Iowa’s qualifications for medical malpractice experts. Prior to 2017, a person could qualify as an expert “if the person’s medical or dental qualifications relate[d] directly to the medical problem or problems at issue and the type of treatment administered in the case.” Iowa Code § 147.139 (2016). This earlier version of the statute “required courts to make a case-by-case determination focused on the proposed expert’s qualifications as they related to the specific problems and treatments at issue.” Jones, 32 N.W.3d at 452. The general assembly abandoned this case-specific approach in 2017. See id. Now, experts must be both “licensed to practice in the same or a substantially similar field as the defendant,” Iowa Code § 147.139(1) (2024), and to have “actively practiced in the same or a substantially similar field” for the past five years, id. § 147.139(2). In addition, if the defendant is “board-certified in a 7 specialty,” the expert must also be “certified in the same or a substantially similar specialty.” Id. § 147.139(3). Finally, if the defendant is “a licensed physician or osteopathic physician under chapter 148,” the expert must be a licensed physician. Id. § 147.139(4)(a). Experts signing certificate of merit affidavits must meet these requirements. Id. § 147.140(1)(a). These qualification standards apply in cases where the defendant is “a health care provider, as defined in section 147.136A,” and the defendant’s standard of care is at issue. Id. § 147.139. Section 147.136A lists a wide variety of health care providers, identified by the statutory provisions governing licensure for each. Id. § 147.136A(1)(a). This list includes physicians “licensed under chapter 148” and physician assistants “licensed under chapter 148C.” Id. We recently considered the “same or a substantially similar” standard used throughout section 147.139 in Jones. 32 N.W.3d at 451–52 (quoting Iowa Code § 147.139(1) (2023)). There, the plaintiff sued the physician who injured her ureter while performing a total hysterectomy, claiming negligence in the surgery and her postoperative care. Id. at 448–49. She designated a board- certified urologist as an expert against the defendant, a physician certified in obstetrics and gynecology. Id. We applied a categorical approach to determine that although the expert and the defendant were licensed and practiced in the same field, they were not certified in substantially similar specialties. Id. at 452, 454. First, to define “field,” we observed that section 147.139 expressly “requires that the qualifying expert be ‘licensed to practice in the same or a substantially similar field’ as the defendant health care provider.” Id. at 451 (quoting Iowa Code § 147.139(1) (2023)). It was also “important to understand the scope of the entire statutory scheme,” which applies the expert-witness 8 qualification requirements to claims involving the standard of care for the full list of “health care providers” in section 147.136A. Id. “Because the statute applies to different categories of health care providers, the most logical interpretation of the qualification provision in section 147.139 is that the term ‘field’ categorically distinguishes one type of health care provider ‘licensed, certified, or otherwise authorized’ to administer health care in this state from another.” Id. (quoting Iowa Code § 147.136A(1)(a) (2023)). We rejected the defendants’ argument that “field” meant a specific practice area, i.e., the practice of urology compared to the practice of obstetrics and gynecology, as inconsistent with the statute’s text. Id. “[B]ecause there is no separate license for obstetrics and gynecology,” or any other specialty, interpreting “field to mean the defendant health care provider’s limited area of practice within a license” would require us to “read[] the word license out of the statute.” Id. An expert and defendant are therefore “licensed in and practice in the same field if they hold the same license and practice under the same license.” Id. In Jones, the expert and defendant satisfied that standard because they were “both licensed physicians, and they both practice[d] medicine.” Id. at 452. Here, the district court described P.A. Fuller as practicing “mainly as a primary care provider in the practice of family medicine” and Dr. Franklin as practicing “in the fields of general surgery, vascular access surgery, and transplant surgery” while working as a trauma surgeon in the emergency department. Without the benefit of Jones, the district court relied on cases from our court of appeals to conclude 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 and a breach of that standard of care.” We reiterate what we said in Jones—a health 9 care provider’s field is coterminous with his license, not a specific area of practice within that license. Id. at 451 (“We thus cannot interpret field to mean the defendant health care provider’s limited area of practice within a license without reading the word license out of the statute, and this we decline to do.”). In light of Jones, the district court erred in focusing on P.A. Fuller and Dr. Franklin’s respective areas of practice within their licenses to conclude they did not practice in the same or substantially similar fields. Following from our determination that field is coextensive with license, we start with the more obvious point—Fuller’s license as a physician assistant under chapter 148C is not “the same” as Dr. Franklin’s license as a physician under chapter 148, so the two are not licensed and do not practice in the same fields for purposes of subsections (1) and (2). We turn then to determine whether physician assistants and physicians are licensed and practice in substantially similar fields. In Jones, the expert satisfied subsections (1) and (2) because he was licensed as a physician and practiced medicine under that license—the same as the defendant. Id. at 452. The case turned on subsection (3) concerning board certifications. Id. at 452, 454. The defendant was board certified in obstetrics and gynecology, so we had to determine whether that specialty was substantially similar to the proposed expert’s certification in urology. Id. at 452. We concluded that specialties are “substantially similar” when they “share a high degree of likeness in their core characteristics such that a practitioner certified in one specialty would, by virtue of that certification alone, possess the foundational knowledge and competence to evaluate and opine on the standard of care applicable to the other specialty.” Jones, 32 N.W.3d at 452–53. This “high degree of likeness” does not require the specialties to be identical. Id. And by focusing 10 on the “certification alone,” we made clear that “the actual problems or treatments at issue in the case” were never germane to this analysis. Id. We identified seven nonexclusive factors relevant to assessing whether specialties are substantially similar: (1) the formal definitions of the specialties, (2) the certifying board structures, (3) the required education and training, (4) the scope of practice, (5) overlap in core and procedural competencies, (6) professional association overlap, and (7) hospital credentialing patterns. Id. at 453. Based on the formal definitions and distinct licensing boards for each specialty, we concluded that urology was not substantially similar to obstetrics and gynecology. Id. at 453–54. We therefore held that the designated expert was not statutorily qualified to testify against the defendant and affirmed dismissal of the case. Id. at 454–55. In Jones, we expressly left for another day “what constitutes a substantially similar field within the meaning of the statute” since the defendant and the expert were licensed in the same field. Id. at 452 (emphasis added). With that issue now before us, we find Jones’s discussion of what constitutes substantially similar specialties provides cogent guidance in making that determination. The general assembly utilized the “same” or “substantially similar” standard in each of subsections (1), (2), and (3) of section 147.139, so we give that phrase a consistent meaning throughout the statute. Iowa Code § 147.139(1)–(3); see also Bribriesco-Ledger v. Klipsch, 957 N.W.2d 646, 650 (Iowa 2021) (“Words and phrases are presumed to bear the same meaning throughout a text.”). Similar to our conclusion that “specialty,” as used in subsection (3), focuses on “certification alone,” Jones, 32 N.W.3d at 452–53, we have concluded that “field,” as used in subsections (1) and (2), likewise focuses on licensure alone, id. at 451; see also Iowa Code § 147.139(1) (“The person is 11 licensed to practice in the same or a substantially similar field as the defendant . . . .”); id. § 147.139(2) (“In the five years preceding the act or omission alleged to be negligent, the person actively practiced in the same or a substantially similar field as the defendant . . . .”). Thus, what we said in Jones with respect to determining whether certifications were substantially similar applies equally to the question of whether fields are substantially similar: the “actual problems or treatments at issue in the case” are not germane to this analysis. 32 N.W.3d at 451–52. This conclusion flows from the general assembly’s 2017 revisions to section 147.139, revisions we must respect. See Wyciskalla v. Iowa Dist. Ct., 588 N.W.2d 403, 407 (Iowa 1998) (“We construe revisions to a statute as altering that statute if the intent to change the law is clear and unmistakable.” (quoting State v. Ahitow, 544 N.W.2d 270, 273 (Iowa 1996))). The definition of “substantially similar” that we adopted in Jones with respect to specialties applies as well to fields. Fields are substantially similar when they share a high degree of likeness in their core characteristics, although not identical, such that a practitioner licensed in one field 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. See Jones, 32 N.W.3d at 452–53. The factors we identified in Jones for determining whether specialties are substantially similar can be adapted to fields as well. The most relevant factors will vary based on the fields or specialties at issue. Here, the respective definitions, scopes of practice, certifying board structures, and education and training requirements for physicians and physician assistants demonstrate that the two fields are substantially similar within the meaning of section 147.139. 12 1. Formal definitions and scopes of practice. Iowa defines both physician assistants and physicians based on a shared “practice of medicine.” A physician assistant is “a person who meets the qualifications under this chapter and is licensed to practice medicine by the board.” Iowa Code § 148C.1(7) (emphasis added). “Physician” is defined as “a person who is currently licensed in Iowa to practice medicine and surgery or osteopathic medicine and surgery.” Id. § 148C.1(6) (emphasis added).1 The “practice of medicine” includes both “[p]ersons who publicly profess to be physicians” and “[p]ersons who act as representatives of any person in doing any of the things mentioned in this section.” Id. § 148.1(1), (3). The importance of this definitional overlap is underscored by the fact that the medical practice nexus does not extend to other health care providers. The Iowa Code expressly excludes several categories of health care providers from the practice of medicine—including most fields listed in section 147.136A(1)(a): podiatrists, chiropractors, all nurses, dentists, optometrists, and pharmacists. See id. § 148.2(4) (including these providers among the “classes of persons” to whom “[s]ection 148.1 shall not be construed to include”). The only section 147.136A(1)(a) providers left as practitioners of medicine are physicians, osteopathic physicians, and physician assistants. Compare id. § 147.136A(1)(a) (listing “health care providers” for purposes of expert testimony), with id. § 148.2(4) (excluding certain health care providers from the practice of medicine). A review of the specific medical services physician assistants can provide also indicates that their scope of practice is substantially similar to physicians. For instance, section 148.1 identifies prescribing medication as engaging in the 1The Iowa Administrative Code provides a similar definition: “a person licensed to practice medicine and surgery or osteopathic medicine and surgery under the laws of this state.” Iowa Admin. Code r. 481—650.1 (flush language). 13 practice of medicine, see id. § 148.1(2), something that physician assistants are expressly authorized to do, see Iowa Admin. Code rs. 481—781.1(1), 481—781.4. And Iowa Code section 148C.4(1) broadly states that “[a] physician assistant may provide any legal medical service for which the physician assistant has been prepared by the physician assistant’s education, training, or experience and is competent to perform.” (Emphasis added.) Administrative rule 481—781.1(2) provides a more detailed, nonexhaustive list of medical services that physician assistants can provide. Iowa Admin. Code r. 481—781.1(2). Those services include assessing, diagnosing, and treating medical and surgical problems, id. r. 481—781.1(2)(b); performing therapeutic and office surgical procedures, id. r. 481—781.1(2)(d)– (e); providing prenatal and postnatal care, id. r. 481—781.1(2)(g); making rounds, performing or assisting with medical procedures, and providing emergency medical services in a hospital setting, id. r. 481—781.1(2)(k); evaluating, treating, and instituting procedures essential to emergency medical problems, id. r. 481—781.1(2)(n); and referring patients to specialists or admitting them to a health care facility, id. r. 481—781.1(2)(m), (p). However, physician assistants can only assist a physician in surgery and in providing obstetrical care, id. r. 481—781.1(2)(f)–(g), suggesting they cannot perform those services independently. The only express prohibition for physician assistants engaging in an independent practice relates to eye exams beyond routine visual screening. Id. r. 481—781.2. It is also worth noting that physician assistants can “[d]irect medical personnel, health professionals, and others involved in caring for patients and the execution of patient care,” and “[h]ealth care providers [must] consider the instructions of a physician [assistant] to be authoritative.” Id. r. 481—781.1(2)(s), 14 (v). In other words, like physicians, they have supervisory authority over other providers. The respective statutory definitions and scopes of practice for physicians and physician assistants suggest that the two practice in substantially similar fields of medicine. 2. Certifying boards. Iowa has designated separate boards for physicians and physician assistants. See Iowa Code § 147.13(1) (designating the board of medicine to administer licensure “[f]or medicine and surgery, osteopathic medicine and surgery, acupuncture, and genetic counseling”); id. § 147.13(2) (designating the board of physician assistants to administer licensure “[f]or physician assistants”); see also id. § 148.3(1) (relating to licensure for physicians); id. § 148C.3 (relating to licensure for physician assistants). In the context of specialties, we held that “[t]he existence of separate certifying boards indicates” the specialties are not substantially similar. Jones, 32 N.W.3d at 453– 54 (noting the “distinct training, examination, and credentialing processes”). There are, however, two areas of overlap between the relevant boards here that were absent in Jones. First, the board of physician assistants is required to “consult[] with the board of medicine” before adopting any licensure rules. Iowa Code § 148C.3(6). Second, the board of physician assistants must include a medical doctor and a doctor of osteopathy. Id. § 147.14(1)(k) (requiring “one member licensed to practice medicine and surgery” and “one member licensed to practice osteopathic medicine and surgery”). This licensure oversight by the board of medicine and the mandatory physician participation on the board of physician assistants reveals that the two boards are not entirely independent, thus distinguishing their relationship from the distinct certifying boards we considered in Jones. See 15 32 N.W.3d at 453–54. The overlap between the boards here supports finding substantial similarity exists between the two fields for purposes of qualifying as experts across the respective fields. 3. Education and training. Iowa requires both physicians and physician assistants to complete an approved course of education that prepares them specifically “to practice medicine,” consistent with the scope of practice for each. Physicians are required to submit evidence of a diploma “or other evidence of equivalent medical education approved by the board” of medicine. Iowa Code § 148.3(1)(a); see also id. §§ 148.2A (defining “board” as the “board of medicine”), .3(1)(b) (requiring passage of “an examination . . . which shall include subjects which determine the applicant’s qualifications to practice medicine”). Physician assistants must “meet[] the qualifications under this chapter and [be] licensed to practice medicine by the board.” Id. § 148C.1(7). These qualifications include graduating from a nationally accredited physician assistant program, id. § 148C.3(1)(a); Iowa Admin. Code r. 481—780.1 (flush language) (defining “approved program”), and “passing the national commission on the certification of physician assistants’ national certifying examination,” Iowa Code § 148C.3(1)(b). Importantly, before physician assistants can practice independently, they must be supervised for two years, Iowa Code § 148C.3(2)(a), by a supervising physician with whom they establish “a mutual understanding of the physician [assistant’s] scope of practice”2 and “areas of medicine performed,” Iowa Admin. 2Chapter 780 of the Iowa Administrative Code governs licensure for “physician associates” rather than “physician assistants.” Iowa Admin. Code r. 481—780.2(1). This reflects a recent evolution in Iowa’s official nomenclature that replaces the term “physician assistant” with “physician associate.” In April 2026, Governor Reynolds signed Senate File 2190 into law; this legislation clarified that “[t]he terms ‘physician assistant’, ‘physician associate’, and ‘P.A.’ are synonymous” under “the Iowa Code and Iowa Administrative Code.” 2026 Iowa Acts ch. 1008, 16 Code. r. 481—780.5(2)(b). The administrative code defines “supervising physician” as “a physician who supervises the medical services provided by the physician [assistant] engaged in independent practice consistent with the physician [assistant’s] education, training, or experience.” Id. r. 481—780.1 (flush language). The requirement for physician oversight before a physician assistant can practice medicine independently further supports a determination that the fields are substantially similar. *** These factors convince us that physicians licensed under chapter 148 and physician assistants licensed under chapter 148C are licensed to practice in substantially similar fields. Aside from specific areas of practice, such as surgery and obstetrics, physician assistants are licensed to independently provide medical services much like a physician. 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).3 Any resulting asymmetry relied upon by Fuller to argue that the general assembly did not intend for physician assistants to be qualified to testify as experts against physicians does not detract from this conclusion. The general assembly addressed such upstream concerns through § 2. This opinion refers to “physician assistants” for clarity and uniformity with the record and usage by the parties. 3The parties do not dispute that Dr. Franklin has practiced under his physician’s license for the five years preceding the medical care giving rise to this litigation, satisfying subsection (2). See Iowa Code § 147.139(2) (“In the five years preceding the act or omission alleged to be negligent, the person actively practiced in the same or a substantially similar field as the defendant . . . .”). 17 subsection (4), which requires experts against licensed-physician defendants to also be licensed physicians. Iowa Code § 147.139(4). Davenport timely served a certificate of merit affidavit signed by a qualified expert, and dismissal of his lawsuit was improper. III. Conclusion. We reverse the district court’s dismissal and remand the case for further proceedings. District court judgment reversed, and case remanded for further proceedings. All justices join this opinion except Christensen, C.J., who takes no part.