Ronnie McDaniel v. Payson Healthcare

IN THE

SUPREME COURT OF THE STATE OF ARIZONA

RONNIE ANTHONY MCDANIEL, CONSERVATOR OF THE ESTATE OF DALLAS
R. HAUGHT; AND ROY G. HAUGHT AND MARIE HAUGHT, NATURAL
PARENTS OF DALLAS R. HAUGHT,
Plaintiffs/Appellants/Cross-Appellees,

v.

PAYSON HEALTHCARE MANAGEMENT, INC., AN ARIZONA CORPORATION,
DBA PAYSON REGIONAL BONE & JOINT; 4C MEDICAL GROUP, P.L.C., AN
ARIZONA CORPORATION; AND AMAR PARKASH SHARMA, M.D.,
Defendants/Appellees/Cross-Appellants.

No. CV-20-0333-PR
Filed July 8, 2022

Appeal from the Superior Court in Gila County
The Honorable Bryan B. Chambers, Judge
No. P0400CV201300157
AFFIRMED IN PART; REMANDED

Opinion of the Court of Appeals, Division Two
250 Ariz. 199 (App. 2020)
VACATED IN PART

COUNSEL:

Arthur E. Lloyd (argued), A. Evan Lloyd, Lloyd Law Group of Arizona,
P.L.L.C., Payson; Thomas P. McGovern, McGovern Law Offices, Phoenix;
and Stanley G. Feldman, Timothy P. Stackhouse, Miller, Pitt, Feldman &
McAnally, P.C., Tucson, Attorneys for Ronnie Anthony McDaniel, Estate of
Dallas R. Haught, Roy G. Haught, and Marie Haught
 MCDANIEL, ET AL. V. PAYSON HEALTHCARE, ET AL.
Opinion of the Court

Kari B. Zangerle, Mary G. Isban (argued), Campbell, Yost, Clare & Norell,
P.C., Phoenix, Attorneys for Payson Healthcare Management, Inc., dba
Payson Regional Bone & Joint

J. Arthur Eaves (argued), Brianna M. Jagelski, Sanders & Parks, P.C.,
Phoenix; and Eileen Dennis GilBride, Jones, Skelton & Hochuli P.L.C.,
Phoenix, Attorneys for 4C Medical Group, P.L.C. and Amar Parkash
Sharma, M.D.

Barry D. Halpern, Ian R. Joyce, Snell & Wilmer L.L.P., Phoenix, Attorneys
for Amici Curiae Arizona Medical Association and American Medical
Association

David L. Abney, Ahwatukee Legal Office, P.C., Phoenix, Attorney for
Amicus Curiae Arizona Association for Justice/Arizona Trial Lawyers
Association

JUSTICE MONTGOMERY authored the opinion of the Court, in which
CHIEF JUSTICE BRUTINEL, VICE CHIEF JUSTICE TIMMER, and
JUSTICES BOLICK, LOPEZ, BEENE, and KING joined.

JUSTICE MONTGOMERY, opinion of the Court:

¶1 To prove negligence in a medical malpractice case, expert
testimony is generally required to establish the separate issues of the
applicable standard of care and that the failure to meet it caused harm. See
A.R.S. § 12-563; Sampson v. Surgery Ctr. of Peoria, LLC, 251 Ariz. 308, 311
¶¶ 13, 16 (2021). The number of retained or specially employed experts that
plaintiffs and defendants may call to testify concerning each issue is
addressed by Arizona Rule of Civil Procedure 26(b)(4)(F)(i). Specifically,
Rule 26(b)(4)(F)(i) allows each side in a case to presumptively call only one
retained or specially employed expert to testify on an issue—hence, the rule
is more commonly known as the “One-Expert Rule.”

¶2 In this case, we consider whether defendants who present
testimony by treating physicians on the standard of care they provided, in
addition to the testimony of a retained or specially employed expert on the
standard of care issue, violate the One-Expert Rule. We also consider
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whether a treating physician who was dismissed from the case on summary
judgment is an indispensable party to a cross-appeal challenging the denial
of a motion to designate him a nonparty at fault.

¶3 We hold that defendants do not violate the One-Expert Rule
when offering the testimony of a treating physician on the standard of care,
in addition to that of a retained or specially employed expert, when the
testimony is based on the treating physician’s observations and personal
participation in providing treatment to the plaintiff. Also, we hold that a
treating physician dismissed on summary judgment is not an indispensable
party to an appeal of the denial of a motion to name him a nonparty at fault.

I. FACTUAL AND PROCEDURAL BACKGROUND

¶4 On July 17, 2011, Dallas Haught cut his knee in a dirt-bike
accident. He went to Payson Regional Medical Center (Payson Regional),
where Dr. Darnell, a surgeon affiliated with defendant Payson Healthcare
Management (PHM), provided initial treatment. After Haught’s knee
injury worsened, he returned to Payson Regional on July 18 and again on
July 19. On July 19, Dr. Darnell ordered a series of tests, including one to
measure Haught’s C-Reactive Protein (CRP) level, a marker for infection
that measures inflammation. Dr. Darnell incorrectly recorded the CRP test
result in Haught’s records, reflecting a reading of 45 instead of 138.79
mg/dl.

¶5 Because Haught’s condition continued to worsen, Dr. Darnell
arranged for his transfer later that same day to Scottsdale Shea Medical
Center. Dr. Sharma, an employee of 4C Medical Group (collectively
“4CMG”) in Scottsdale, saw Haught on his arrival and prepared an initial
report that omitted the CRP result. Over the course of Haught’s stay, Drs.
Burge, Cory, Friedman, Schaub, and Sharma participated in treating his
injury. No one ordered another CRP test.

¶6 At some point, Haught developed necrotizing fasciitis,
resulting in the surgical removal of all the skin on his right leg. Through
his conservator, Ronnie McDaniel, Haught subsequently sued several
healthcare providers, including PHM, Dr. Cory, and 4CMG for medical
negligence. He alleged that the failure to accurately communicate the CRP
test result delayed the diagnosis of necrotizing fasciitis and caused the need
for greater surgical intervention leading to permanent injuries and
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disfigurement.

¶7 Before trial, Dr. Cory moved for summary judgment “due to
[Haught’s] failure to show that any alleged breach of the standard of care
by [him] caused and or contributed to any of Dallas Haught’s actual
injuries.” Neither Haught nor any other party opposed the motion and the
trial court granted it, entering judgment in favor of Dr. Cory. PHM
thereafter requested the trial court withdraw the order granting summary
judgment in favor of Dr. Cory and filed a motion to name him a nonparty
at fault. 1 The trial court denied the withdrawal motion as untimely and
denied the motion to name Dr. Cory a nonparty at fault without
explanation. Thereafter, PHM sought special action review of the trial
court’s ruling on the motion for summary judgment. The court of appeals
declined jurisdiction.

¶8 At trial, defendants PHM and 4CMG called Drs. Berge, Cory,
Friedman, and Schaub to testify and made clear at the outset of their
testimony that each was not a “paid expert.” Defendants’ disclosure
statements indicated that each of them would testify as a treating physician.
Specifically, Drs. Berge and Cory would testify “consistent[] with the
medical records,” their depositions, and their recollection, and about their
“care and treatment” of Haught, “including [their] personal observations of
and interactions with him.” Drs. Friedman and Schaub would likewise
testify “consistent with the medical records and [their] recollection.”

¶9 Haught argued throughout the trial that the defense elicited
expert testimony from the treating physicians, thereby violating the One-
Expert Rule. Specifically, Haught argued that by asking questions he
characterized as hypothetical concerning the CRP result and infectious
disease, the defendants elicited testimony that went beyond the treating
physicians’ personal knowledge of the care they provided, rendering them
expert witnesses. Therefore, because the treating physicians testified to the
same issues as the defendants’ retained experts, the defendants presented

1 A defendant may seek to name a nonparty at fault so that the jury may
consider the nonparty with other defendants in apportioning fault for any
or all of a plaintiff’s injuries. See A.R.S. § 12-2506(B). Because damages are
calculated based on the percentage of fault allocated to each defendant, any
fault attributed to a nonparty can reduce a defendant’s damages liability.
See § 12-2506(A).
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more experts than allowed.

¶10 After a sixteen-day trial, the jury returned a verdict for the
defendants and the trial court entered judgment on their behalf. Haught
moved for a new trial based on three issues: alleged juror misconduct;
violation of the One-Expert Rule; and defense presentation of previously
undisclosed expert opinions. The trial court denied the motion. The court
concluded that how to diagnose necrotizing fasciitis and what to look for
was “relevant” in the testimony of the treating physicians as “factual
witnesses” and that the One-Expert Rule was not violated. With respect to
undisclosed expert opinions, the court held that the “plaintiffs had plenty
of opportunity to cross-examine those witnesses on that to reveal that this
isn’t what they said originally.” And the court found there was no juror
misconduct.

¶11 Haught appealed the defense judgment and the denial of his
motion for a new trial. PHM cross-appealed the denial of its motion to
name Dr. Cory a nonparty at fault.

¶12 With respect to Haught’s claims, the court of appeals reversed
the trial court and remanded for a new trial. McDaniel v. Payson Healthcare
Mgmt., Inc., 250 Ariz. 199, 203 ¶ 1 (App. 2020). In a de novo review, id.
at 204 ¶ 8, the court held that the treating physicians’ testimony addressing
the CRP test was expert testimony related to the standard of care and
violated the One-Expert Rule, id. at 206 ¶ 16. Additionally, the court held
that the trial court should have excluded the undisclosed expert opinions
presented by the defense. Id. at 208 ¶ 26. Because the court determined it
was necessary to remand for a new trial, it did not address the alleged juror
misconduct. Id. ¶ 27. As for PHM’s cross-appeal, the court concluded that
Dr. Cory was an indispensable party, and that, because PHM had not
notified him of the cross-appeal, the court lacked jurisdiction and dismissed
it. Id. at 210 ¶ 35.

¶13 We granted review to address whether the court of appeals
erred in using a de novo standard of review concerning the One-Expert
Rule and in concluding that the presentation of the treating physicians’
testimony on the standard of care violated that rule, and whether the court
also erred in determining that it lacked jurisdiction to consider PHM’s
cross-appeal due to the failure to include Dr. Cory. These are recurring
issues of statewide importance. We have jurisdiction pursuant to article 6,
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section 5(3), of the Arizona Constitution.

II. ONE-EXPERT RULE

A. Standard of Review

¶14 As an initial matter, the parties contest whether the applicable
standard of review is abuse of discretion or de novo. 4CMG and PHM
argue that determining whether a treating physician testified as a fact or
expert witness is a threshold matter subject to an abuse-of-discretion
standard. Haught argues that because this matter involves the
interpretation of the Rules of Civil Procedure, our review is de novo. Both
parties are correct. Whether the defendants violated the One-Expert Rule
is a mixed question of law and fact. In such a case, “we defer to the trial
court’s factual findings but review de novo all legal conclusions.” Helvetica
Servicing, Inc. v. Pasquan, 249 Ariz. 349, 352 ¶ 10 (2020).

B. Analysis and Application

¶15 Haught argues that by answering hypothetical questions
about CRP test results and the potential impact on his treatment, the
treating physicians testified as experts, which violated the One-Expert Rule.
4CMG, joined by PHM, argues that the treating physicians’ testimony
contained only factual, treatment-related testimony.

¶16 “We interpret court rules according to the principles of
statutory construction.” Phillips v. O’Neil, 243 Ariz. 299, 301 ¶ 8 (2017)
(quoting State v. Aguilar, 209 Ariz. 40, 47 ¶ 23 (2004)). “The primary goal in
interpreting a rule is to give effect to the intent of the rule-makers.” Chronis
v. Steinle, 220 Ariz. 559, 560 ¶ 6 (2009).

¶17 At its inception in 1991, the One-Expert Rule read:

Each side shall presumptively be entitled to only one
independent expert on an issue. Where there are multiple
parties on a side and the parties cannot agree as to which
independent expert will be called on an issue, the court shall
designate the independent expert to be called or, upon the
showing of good cause, may allow more than one

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independent expert to be called.

Ariz. R. Civ. P. 26(b)(4)(D) (1991) (emphasis added).

¶18 The court of appeals addressed the term “independent
expert” in 2014 in Felipe v. Theme Tech Corp., 235 Ariz. 520, 526 ¶ 19 (App.
2014). The court found the word “independent” ambiguous, because it
could refer to someone who was “not paid by one side or the other to form
his opinions and testify about them,” id. at 525 ¶ 17, or it “could mean a
retained expert who is independent of any party prior to retention,” id. at
526 ¶ 19. Relying on the 1991 committee comment that stated “[t]he words
‘independent expert’ in this rule refer to a person who will offer opinion
evidence [and] who is retained for testimonial purposes,” id. at 525 ¶ 17, the
court defined an independent expert as “a person who is retained for the
purpose of offering expert opinion testimony,” id. at 526 ¶ 19.

¶19 Substantive and organizational changes made to Rule
26(b)(4)(D) in 2016 incorporated Felipe’s definition. Rule 26(b)(4)(D) (2016).
In 2018, the Rule was redesignated as Rule 26(b)(4)(F)(i) and (ii). Order No.
R-18-0007 (2018). The One-Expert Rule currently reads:

Generally. Unless the parties agree or the court orders
otherwise for good cause, each side is presumptively entitled
to call only one retained or specially 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.

Rule 26(b)(4)(F)(i) (emphasis added).

¶20 Despite the various amendments to the One-Expert Rule, the
1991 committee comment continues to inform the application of the Rule.
Cf. State v. Whitman, 234 Ariz. 565, 567 ¶ 9 (2014) (providing that
comments to rules inform our interpretation). Importantly for our analysis,
in addition to clarifying who is an independent expert, the 1991 committee
comment also made clear that an independent expert “is not a witness to
the facts giving rise to the action.” Rule 26(b)(4), cmt. to 1991 amendment.
Additionally, the committee comment stated that “[t]here is no intent to
preclude witnesses who in addition to their opinion testimony are factual
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witnesses.” Id. Taken together, these two points clarify that a fact witness
may also offer expert opinion testimony without violating the One-Expert
Rule when the witness’ testimony is based on personal observations and
actions. 2 Therefore, the dispositive inquiry is whether the treating
physicians testified based on their observations and actions in treating
Haught, regardless of whether in explaining their treatment decisions they
also offered opinions about the standard of care.

¶21 Drs. Berge, Cory, Friedman, and Schaub were specifically
disclosed as treating physicians who would testify to facts arising from
their treatment of Haught, see supra ¶ 8, and the trial court found they
testified as fact witnesses. As for specific testimony concerning the CRP test
and its result in the context of Haught’s necrotizing fasciitis, the trial court
concluded that it was relevant to their testimony as fact witnesses. We
agree. To the extent the treating physicians were asked questions
concerning the CRP test and its result, their answers were clearly in the
context of explaining the treatment they personally provided and did not
constitute impermissible expert testimony. See In re Commitment of
Frankovitch, 211 Ariz. 370, 374 ¶¶ 11–12 (App. 2005) (finding no violation of
former version of One-Expert Rule where psychiatrist performing a
psychological examination was “more akin to a ‘witness to the facts giving
rise to the action’ than to an expert ‘retained for testimonial purposes’”
(quoting Rule 26(b)(4) cmt. to 1991 amendment)); Ariz. Dep’t of Revenue v.
Superior Court, 189 Ariz. 49, 53 (App. 1997) (finding no violation of former
version of One-Expert Rule where employee’s “opinion as to valuation was
formed in the course and scope of his regular duties as an appraiser and not
in anticipation of testifying at trial”); see generally Stafford v. Burns, 241 Ariz.
474, 481–82 ¶¶ 25–27 (App. 2017) (concluding that alleged hypothetical
questions concerning methadone ingestion and overdose “provided both
an illustration of the extent of [defendant treating physician’s] knowledge
of the relevant area of medical practice and the basis for [her] opinion that
she did not violate the standard of care”).

2 Nonetheless, if a treating physician will offer expert opinion testimony,
the defense must comply with specific discovery and disclosure obligations
pursuant to Arizona Rules of Civil Procedure 26(b)(4) and 26.1,
respectively. See also Solimeno v. Yonan, 224 Ariz. 74, 76 ¶ 1 (App. 2010)
(stating that “a medical malpractice defendant who also testifies as a
standard of care expert is subject to expert disclosure requirements
regarding that issue”).
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¶22 Because the treating physicians’ testimony concerning the
standard of care, including their expert opinions, was based on personal
observations and personal participation in Haught’s treatment, the
defendants did not violate the One-Expert Rule in presenting their
testimony, even if the defense also presented standard-of-care testimony
from another retained expert. The trial court correctly declined to find a
violation of the One-Expert Rule. 3

C. Cumulative Testimony

¶23 Haught warns that permitting treating physicians to testify as
they did in this case will permit medical malpractice defendants to
overwhelm jurors with a “deluge” of expert opinions and present
cumulative testimony on an issue. The defense would then be able to
argue—as it did here—that thirteen doctors testified that the standard of
care was met as compared to just one expert presenting the countervailing
conclusion for the plaintiff. Haught misapprehends the primary purpose
of the One-Expert Rule, which is to limit the cost of the presentation of
multiple retained experts. See Rule 26(b)(4) cmt. to 1991 amendment
(stating that the purpose “is to avoid unnecessary costs inherent in the
retention of multiple independent expert witnesses”). It is Arizona Rule of
Evidence 403 that directly governs instances of multiple experts presenting
cumulative evidence.

¶24 Rule 403 explicitly permits a trial court to “exclude relevant
evidence if its probative value is substantially outweighed by a danger of
. . . needlessly presenting cumulative evidence.” And, in the instance of
retained and non-retained experts offering the same opinion evidence, “[a]
trial court certainly has the discretion to prevent the presentation of
‘cumulative evidence.’” Felipe, 235 Ariz. at 526 ¶ 21 (quoting Rule 403).
Consequently, a court may preclude expert testimony if it “augments or
tends to establish a point already proved by other evidence” whether it
comes from a treating physician or a retained expert. Id. ¶ 22 (quoting State
v. Kennedy, 122 Ariz. 22, 26 (App. 1979)).

3Given that the treating physicians here are not defendants in this lawsuit,
we need not address the parties’ arguments concerning the meaning of Rule
26(b)(4)(F)(ii), which applies to defendants in medical malpractice actions.
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¶25 With respect to being outnumbered, we note that the
limitation of one expert per side on an issue is a presumption subject to
modification by the parties or by a court’s “order[] otherwise for good
cause.” Rule 26(b)(4)(F)(i). We also observe that the 1991 committee
comment further provided that “[w]here an issue cuts across several
professional disciplines, the court should be liberal in allowing expansion
of the limitation upon experts established in the rule.” Rule 26(b)(4) cmt. to
1991 amendment. Thus, a plaintiff may be entitled to additional experts
under appropriate circumstances to fairly meet a “deluge” of defense
expert witnesses.

III. PHM’S CROSS-APPEAL

A. Jurisdiction

¶26 The court of appeals concluded it did not have jurisdiction to
consider PHM’s cross-appeal because Dr. Cory was an indispensable party
and did not receive notice. McDaniel, 250 Ariz. at 210 ¶ 35. The court
reasoned that for PHM to successfully challenge the trial court’s denial of
its motion to name Dr. Cory a nonparty at fault, the court would have to
vacate the order entering summary judgment that dismissed him from the
case. Id. ¶ 33. Therefore, Dr. Cory “had an interest in opposing PHM’s
[petition] to review the [trial] court’s denial and underlying summary
judgment ruling on appeal . . . and failing to permit [Dr.] Cory to be heard
on the matter would prejudice him.” Id. ¶ 34.

¶27 PHM argues that the cross-appeal could be decided without
considering the trial court’s summary judgment order because § 12-2506(B)
provides that the “[a]ssessment of fault against nonparties does not subject
any nonparty to liability in this or any other action, and it may not be
introduced as evidence of liability in any action.” Therefore, if the trial
court erred in denying the motion, Dr. Cory cannot be subject to any
liability and no review of the order granting him summary judgment is
necessary. Thus, he does not have an interest in the resolution of whether
the trial court improperly denied PHM’s motion.

¶28 Haught argues that overturning the trial court’s denial of
PHM’s motion to name Dr. Cory a nonparty at fault necessarily requires
vacating the summary judgment order. This is because the trial court
determined, in granting the motion for summary judgment, that Dr. Cory
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was not at fault for Haught’s injuries. PHM’s cross-appeal therefore
implicates a substantial right of Dr. Cory, rendering him an indispensable
party and leaving the court of appeals without jurisdiction.

¶29 A cross-appeal may be dismissed for lack of jurisdiction when
a cross-appellant fails to include an indispensable party. See Burrows v.
Taylor, 129 Ariz. 212, 213 (App. 1981). An indispensable party is one who
“has an interest in opposing the object sought to be accomplished by the
appeal.” Marriott Corp. v. Indus. Comm’n, 147 Ariz. 116, 118 (1985) (quoting
Dunn v. Law Offs. of Ramon R. Alvarez, 119 Ariz. 437, 440 (App. 1978)).

¶30 As noted above, § 12-2506(B) precludes liability for a
nonparty and no assessment of fault may be used as evidence “in any
action.” Thus, even if the court of appeals had vacated the trial court’s
ruling on PHM’s motion and permitted Dr. Cory to be named a nonparty
at fault, he cannot be subject to liability as a matter of law. Therefore, absent
any risk of liability, Dr. Cory could have no interest in and no reason to
oppose PHM’s cross-appeal and was not an indispensable party. The court
of appeals therefore erred in concluding it did not have jurisdiction over
PHM’s cross-appeal.

B. Nonparty at Fault

¶31 Because the parties have fully briefed and argued the cross-
appeal, we exercise our discretion to decide in the first instance whether the
trial court erred by denying PHM’s motion to name Dr. Cory a nonparty at
fault. See generally Lewis v. N.J. Riebe Enters., Inc., 170 Ariz. 384, 394 (1992)
(deciding issues not addressed by the court of appeals “[i]n the interest of
judicial economy”); Schwab v. Matley, 164 Ariz. 421, 422 n.2 (1990) (noting
that “[p]rinciples of judicial economy” supported deciding an issue that
had been briefed and argued). We review the trial court’s ruling for an
abuse of discretion, Bowen Prods., Inc. v. French, 231 Ariz. 424, 427 ¶ 9 (App.
2013), and will uphold it if there is “any reasonable evidence in the record
to sustain it,” State v. Morris, 215 Ariz. 324, 341 ¶ 77 (2007) (quoting State v.
Veatch, 132 Ariz. 394, 396 (1982)).

¶32 PHM argued in its motion to the trial court that because
Haught did not oppose Dr. Cory’s motion for summary judgment, Haught
voluntarily dismissed Dr. Cory. PHM therefore cited LyphoMed, Inc. v.
Superior Court, 172 Ariz. 423, 427 (App. 1992), for the proposition that
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“[w]here a plaintiff dismisses a claim against a defendant, having entered
into a settlement agreement with that defendant, the trier-of-fact may
apportion the fault of that defendant regardless of whether another
defendant has given notice of non-party at fault.” PHM concluded its
motion by requesting an order pursuant to § 12-2506(B) to name Dr. Cory a
nonparty at fault.

¶33 Section 12-2506(B) specifies that “[n]egligence or fault of a
nonparty may be considered if the plaintiff entered into a settlement agreement
with the nonparty . . . .” (Emphasis added.) But there is no evidence of a
settlement agreement between Haught and Dr. Cory in the record, or of
Haught voluntarily dismissing him. See Ariz. R. Civ. P. 41(a) (permitting a
plaintiff to voluntarily dismiss a claim against a defendant under specified
circumstances by filing a notice of dismissal or by order of the court). Dr.
Cory’s dismissal from the case was the result of the trial court entering an
order granting his motion for summary judgment “as to all claims against”
him and entering judgment against Haught.

¶34 Even more of a problem for PHM’s argument is that a trial
court may only instruct a jury about a nonparty’s comparative fault “if
evidence offered at trial is adequate to support the jury finding that the
nonparty was negligent.” Ryan v. S.F. Peaks Trucking Co., 228 Ariz. 42, 48
¶ 22 (App. 2011) (quoting A Tumbling-T Ranches v. Flood Control Dist. of
Maricopa Cnty., 222 Ariz. 515, 540 ¶ 83 (App. 2009)). However, the trial court
entered an order granting summary judgment for Dr. Cory on the basis that
he could not have caused any of Haught’s injuries. See supra ¶ 7; see also
Orme Sch. v. Reeves, 166 Ariz. 301, 309 (1990) (discussing the purpose of a
motion for summary judgment and noting its use when “there is no issue
of fact and . . . the movant is entitled to judgment as a matter of law”). Thus,
there was no evidence that could have supported a finding that Dr. Cory,
whether as a named defendant or a nonparty at fault, was negligent. See
Ryan, 228 Ariz. at 48 ¶ 22 (stating that a defendant “must prove the
nonparty is actually at fault”).

¶35 Because there were no grounds to allow PHM to name Dr.
Cory a nonparty at fault under § 12-2506(B), nor any basis upon which the
court could have instructed a jury to determine any fault on his part, the
trial court did not err in denying PHM’s motion to name Dr. Cory a
nonparty at fault.

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IV. DISPOSITION

¶36 While our resolution of the issues concerning the One-Expert
Rule and a nonparty at fault would otherwise result in a reinstatement of
the defense verdict, the court of appeals’ resolution of the undisclosed
expert opinions issue, for which we did not grant review, raises the
question of whether this case should still be remanded for a new trial. See
McDaniel, 250 Ariz. at 208 ¶ 26. 4CMG asserted that the court’s failure to
expressly order remand as to undisclosed expert opinions establishes its
intent not to do so. On the other hand, Haught noted the court referenced
“reasons”—plural—for reversing the trial court and remanding for a new
trial, thus demonstrating that the court’s decision to remand rested on the
undisclosed opinions issue in addition to the One-Expert Rule violation.
See id. at 203 ¶ 1 (ordering “[f]or the following reasons . . . remand for a new
trial”).

¶37 Under Arizona Rule of Civil Procedure 37(c)(1), a party “may
not use . . . at trial” information that was not timely disclosed. See also
Englert v. Carondelet Health Network, 199 Ariz. 21, 25 ¶ 6 (App. 2000) (noting
that a failure to timely disclose information concerning the expected
testimony of an expert results in an inability “to use that information at trial
absent specific extenuating circumstances”). And an “error in the
admission or rejection of evidence” may serve as the basis for granting a
new trial. Ariz. R. Civ. P. 59(a)(1)(F); see also Englert, 199 Ariz. at 25 ¶ 5
(asserting trial court’s discretion to grant new trial when it makes an “error
in admitting evidence that materially affects a party’s rights”). Prejudicial
evidentiary rulings may also provide grounds for a new trial. See Kott v.
City of Phoenix, 158 Ariz. 415, 417–19 (1988) (remanding for new trial in case
where opinion testimony not disclosed); In re Conservatorship for Hardt, 242
Ariz. 449, 451 ¶ 1 (App. 2017) (remanding for a new trial based on
erroneous, prejudicial exclusion of testimony).

¶38 While the court of appeals did not explicitly order remand
after analyzing the issue of undisclosed expert opinions, the court did
expressly find that “both [4CMG] and PHM failed to disclose changes in
the opinions of two experts.” McDaniel, 250 Ariz. at 206 ¶ 17, 208 ¶ 25.
These changes “prevented Haught from effectively preparing for” defense
testimony. Id. at 208 ¶ 26. Because the new expert opinions were not
disclosed before trial, the court concluded that “the trial court abused its
discretion in permitting the undisclosed opinions into evidence.” Id.
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¶39 Given the court of appeals’ analysis, by finding the trial court
abused its discretion and that Haught suffered prejudice, the court
established the basis for overturning the admission of the undisclosed
opinions. Id. at 206–07 ¶ 17 (“We will not overturn a court’s ruling
admitting or excluding evidence absent prejudice.”). Because this was a
prejudicial admission of an undisclosed expert opinion, the court had a
basis, independent of the violation of the One-Expert Rule, to remand the
case for a new trial. See Kott, 158 Ariz. at 417–19 (remanding for new trial
in case where opinion testimony not disclosed).

¶40 We therefore conclude that the “reasons” upon which the
court of appeals remanded the matter for a new trial included the issue of
the admission of the undisclosed expert opinions. Consequently, our
determination that the defendants did not violate the One-Expert Rule does
not obviate the need to remand for a new trial.

V. CONCLUSION

¶41 We vacate ¶¶ 7–16 and 29–35 of the court of appeals’ opinion
concerning the One-Expert Rule and PHM’s cross-appeal. We affirm the
trial court’s ruling concerning the testimony of the treating physicians and
its denial of PHM’s motion to name Dr. Cory a nonparty at fault and
remand for a new trial.

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