                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

DANIEL JERDEN; CATRINA JERDEN,            No. 04-35889
             Plaintiffs-Appellants,          D.C. No.
               v.
                                         CV-02-03056-JPC
PAUL G. AMSTUTZ, M.D.,                     ORDER AND
              Defendant-Appellee.           AMENDED
                                            OPINION

       Appeal from the United States District Court
                for the District of Oregon
       John P. Cooney, Magistrate Judge, Presiding

                 Argued and Submitted
          September 13, 2005—Portland, Oregon

                 Filed December 9, 2005
                Amended January 12, 2006

     Before: Raymond C. Fisher, Ronald M. Gould, and
               Carlos T. Bea, Circuit Judges.

                 Opinion by Judge Gould




                            575
578                  JERDEN v. AMSTUTZ


                       COUNSEL

Megan B. Annand, Law Office of Megan B. Annand, Med-
ford, Oregon, for the plaintiffs-appellants.

Robert L. Cowling (argued) and Benjamin M. Bloom, Cowl-
ing, Heysell, Plouse, Ingalls & Moore, Medford, Oregon, for
the defendant-appellee.
                      JERDEN v. AMSTUTZ                        579
                           ORDER

  The opinion filed on December 9, 2005 and published at
430 F.3d 1231 is AMENDED as follows.

Slip Op. p. 16121: The first sentence in the third paragraph
states:

    During the trial, on Wednesday, May 26, 2004, Dr.
    Gross testified for Plaintiffs, stating that an ordinar-
    ily reasonable surgeon would not have made the
    incorrect diagnosis and would have referred the
    patient to a neurologist before conducting the opera-
    tion.

This sentence is deleted in its entirety and replaced with the
following language:

    During the trial, on Wednesday, May 26, 2004, Dr.
    Gross testified for Plaintiffs, stating that the MRI
    reports taken on June 20, 2000 were “highly suspi-
    cious” of multiple sclerosis; that he had been
    referred cases from neurosurgeons who had looked
    at MRI reports that were suspicious of multiple scle-
    rosis; and that in his experience as a neurologist,
    when a neurosurgeon is suspicious of multiple scle-
    rosis, a referral is made to a neurologist. Dr. Gross
    also testified as to what as a neurologist he would
    have done or recommended, rather than a cranio-
    tomy, had he been consulted on MRI reports such as
    these in the case where a patient had complained of
    numbness.

   With this amendment, the panel votes to deny the petition
for rehearing. Defendant-Appellee’s petition for panel rehear-
ing is DENIED. No further petitions for panel rehearing or for
rehearing en banc shall be entertained.
580                    JERDEN v. AMSTUTZ
  IT IS SO ORDERED.


                           OPINION

GOULD, Circuit Judge:

   In this diversity case, Plaintiffs-Appellants Mr. Daniel and
Ms. Catrina Jerden (“Plaintiffs”) brought a claim of medical
negligence against Defendant-Appellee Dr. Paul G. Amstutz
(“Defendant”) after Defendant, a neurosurgeon, mistakenly
diagnosed Mr. Jerden as having a brain tumor based partly on
Defendant’s interpretation of magnetic resonance imaging
(MRI) reports. Defendant conducted invasive and unwar-
ranted brain surgery on Mr. Jerden before the correct diagno-
sis of multiple sclerosis was made.

   Plaintiffs appeal from the judgment entered against them
after a jury trial resulted in a verdict for Defendant, contend-
ing that the district court committed reversible error warrant-
ing a new trial. Plaintiffs assert that there was reversible error
based on: (1) the granting of Defendant’s motion for a limit-
ing instruction to the testimony of Plaintiffs’ expert witness,
Dr. Karl Gross, on the last day of trial; (2) the actual jury
instruction limiting Dr. Gross’s testimony; (3) the testimony
of Defendant’s witness, Mr. Don Bowser, relating to his opin-
ion of the magnetic resonance angiogram (MRA) report; and
(4) the district court’s denial of Plaintiffs’ motion for a new
trial in light of the above claims and newly discovered evi-
dence that Defendant has a prosthetic eye. We agree that there
was error in the granting of a motion limiting the jury’s con-
sideration of Dr. Gross’s testimony, and error with regard to
admission of Mr. Bowser’s opinion concerning the MRA
report. We reverse and remand.

                                I

  In June 2000, Mr. Jerden was referred to Dr. Amstutz, who
was called upon to evaluate an unknown illness. After exam-
                      JERDEN v. AMSTUTZ                    581
ining MRI reports of Mr. Jerden, Dr. Amstutz made a diagno-
sis that Mr. Jerden had a brain tumor and recommended a
craniotomy. On July 10, 2000, Dr. Amstutz performed a
craniotomy on Mr. Jerden, who was thereafter correctly diag-
nosed with multiple sclerosis based on pathology analysis of
the brain tissue removed during the operation.

   Plaintiffs, in their action for medical negligence, asserted
that a less invasive biopsy would have had fewer physical
implications and would have allowed a greater possibility of
recovery from the effects of the plaques formed in the brain
by the demyelination associated with multiple sclerosis. Plain-
tiffs alleged that Defendant failed to review adequately the
diagnostic MRI reports, radiology reports, and Mr. Jerden’s
medical history and symptoms, which indicated signs of mul-
tiple sclerosis. Plaintiffs also contended that Defendant was
negligent for failing to use less intrusive diagnostic methods
than the craniotomy and for failing to consult with qualified
specialists such as neurologists.

   The jury trial commenced on May 24, 2004. As pertinent
to this appeal, Plaintiffs presented testimony from two medi-
cal doctors, Dr. Karl Gross, a neurologist, and Dr. Martin
Johnson, a neurosurgeon, who both testified that Defendant
breached his standard of care and that this breach was the
cause of Plaintiffs’ injuries. Defendant countered with the
presentation of medical testimony from Dr. Elaine Edmonds,
a neurologist, and Dr. Edward A. Neuwelt, a neurosurgeon,
who both testified that the initial diagnosis of a brain tumor
was reasonable under the circumstances. In addition, the jury
heard testimony from Defendant Dr. Amstutz and from a
neurosurgical nurse practitioner, Mr. Bowser, who had
worked with Defendant since 1997 and who had assisted Dr.
Amstutz during Mr. Jerden’s operation.

  After a six-day trial, the jury returned a verdict for the
Defendant on June 1, 2004. On June 16, 2004, Plaintiffs filed
582                        JERDEN v. AMSTUTZ
their motion for new trial which was denied on September 3,
2004. Plaintiffs appeal.

                                    II

  We first consider Plaintiffs’ contention that the district
court erred by granting a motion to strike testimony of Dr.
Gross, a neurologist, and instructing the jury that it could not
consider his testimony on the issue of negligence.1

   [1] Oregon has adopted a locality rule in medical malprac-
tice actions whereby physicians have “the duty to use that
degree of care, skill and diligence that is used by ordinarily
careful physicians or podiatric physicians and surgeons in the
same or similar circumstances in the community of the physi-
cian or podiatric physician and surgeon or a similar communi-
ty.” Or. Rev. Stat. § 677.095 (2003) (last amended Aug. 5,
1997). Pursuant to Federal Rule of Evidence 601, the district
court was required to follow the Oregon locality rule when
presented with the testimony of out-of-town medical experts
who testify as to the appropriate standard of care for local
physician defendants. Under this evidentiary rule, out-of-town
experts must show “knowledge of what is proper conduct by
practitioners in the community or a similar community under
circumstances similar to those which confronted the defen-
dant.” Creasey v. Hogan, 637 P.2d 114, 122 (Or. 1981).

   During the trial, on Wednesday, May 26, 2004, Dr. Gross
testified for Plaintiffs, stating that the MRI reports taken on
June 20, 2000 were “highly suspicious” of multiple sclerosis;
that he had been referred cases from neurosurgeons who had
looked at MRI reports that were suspicious of multiple sclero-
sis; and that in his experience as a neurologist, when a neuro-
surgeon is suspicious of multiple sclerosis, a referral is made
  1
    We review rulings to admit or exclude evidence for an abuse of discre-
tion and will not reverse absent prejudice. Watec Co., Ltd. v. Liu, 403 F.3d
645, 650 n.3 (9th Cir. 2005).
                          JERDEN v. AMSTUTZ                         583
to a neurologist. Dr. Gross also testified as to what as a neu-
rologist he would have done or recommended, rather than a
craniotomy, had he been consulted on MRI reports such as
these in the case where a patient had complained of numb-
ness. Dr. Gross did not expressly testify that he had knowl-
edge of the proper medical conduct within Defendant’s
community or a similar community. During the testimony of
Dr. Gross, counsel for Defendant objected based on “lack of
foundation, lack of qualification as to what a surgeon should
do,” after asking Dr. Gross if he ever practiced surgery.
Although the district court did not at this time make a ruling
concerning this objection, Plaintiffs’ counsel in substance
cured this objection by asking Dr. Gross about his
professional experience as a neurologist working with neuro-
surgeons. See Creasey, 637 P.2d at 118 (allowing the testi-
mony of medical experts from another discipline in medical
malpractice actions on matters where the principles of both
schools concur).

   On May 28, 2004, Defendant moved to strike the portion
of Dr. Gross’s testimony relating to whether Defendant satis-
fied his standard of care. The record is not crystal clear on
whether the basis for the motion was disclosed when it was
made on May 28th, or on the last day of trial, June 1st, when
the motion was granted. However, this potential difference is
not material to our analysis which proceeds on the assumption
that the basis was disclosed on May 28, two days after Dr.
Gross’s testimony had concluded. Defendant argued that Dr.
Gross’s testimony relating to Defendant’s standard of care
was inadmissible because Dr. Gross, in his testimony two
days earlier, had not stated that he was familiar with the
proper medical conduct in Defendant’s community in compli-
ance with the foundational requirement under Creasey.2 The
  2
   An expert can satisfy this requirement without actual knowledge of the
defendant’s community and may even testify that a nationally uniform
standard of care should govern the defendant’s conduct. See Mosley v.
Owens, 816 P.2d 1198, 1201-1202 (Or. Ct. App. 1991). Furthermore,
584                         JERDEN v. AMSTUTZ
court granted the Defendant’s motion to strike on June 1, con-
cluding that a necessary predicate for the testimony was not
given, which the court described as a lack of “magic words.”3
Shortly thereafter, the court instructed the jury: “You have
heard testimony from Karl Gross, M.D. This testimony should
be considered by you for a limited purpose only. You are
instructed that you may not use any of Dr. Gross’ testimony
as a basis for deciding whether Dr. Amstutz was negligent.”

   Plaintiffs have argued on appeal that the limiting instruc-
tion regarding Dr. Gross’s testimony should not have been
given because the objection was untimely, and because the
phrasing of the instruction was overbroad. We focus on the
first contention, and consider the issue of the timeliness of the
objection to be dispositive in our assessment of whether trial
error by the district court occurred.4

Defendant Dr. Amstutz himself introduced testimony of an out-of-town
neurologist stating an opinion as to Defendant’s standard of care which
was admitted after the neurologist acknowledged that she was familiar
with the standard of care governing the locality. Defendant’s witness
expressly testified that she was “familiar with the appropriate methods of
practice for doctors who take care of patients with MS and physicians who
actually diagnose MS such as Dr. Amstutz, who is a neurosurgeon in this
case practicing in Klamath Falls” and that she was “familiar with what is
appropriate care for those neurosurgeons under these circumstances.”
   3
     In ruling on the Defendant’s motion, the district court stated: “The
Court invited counsel to show the Court where in the transcript of Dr.
Gross’s testimony there was that necessary predicate. And counsel quite
candidly has said that the magic words, if you will, are not there or remain
— that she cannot find them either.”
   4
     Because Plaintiffs did not object to the wording of the instruction, their
challenge to the ambiguous language is waived. Fed. R. Civ. P. 51. Plain-
tiffs’ opposition to the motion to strike did not alert the district court to
Plaintiffs’ particular concerns about the language of the instruction and in
our view the lack of a specific objection on this ground cannot be justified
based on the “pointless formality” exception. Voohries-Larson v. Cessna
Aircraft Co., 241 F.3d 707, 714 (9th Cir. 2001). We have recognized only
a limited sphere for plain error in a civil case. As we held in Bird v. Gla-
                           JERDEN v. AMSTUTZ                           585
   The rule requiring timely objection to evidence in federal
trials is set forth explicitly in the Federal Rules of Evidence.
“Error may not be predicated upon a ruling which admits or
excludes evidence unless a substantial right of the party is
affected, and . . . a timely objection or motion to strike
appears of record, stating the specific ground of objection, if
the specific ground was not apparent from the context . . . .”
Fed. R. Evid. 103 (2005).

   [2] This rule is reflected in the guidance of a respected pro-
cedural treatise. “An objection must be made as soon as the
ground of it is known, or could reasonably have been known
to the objector, unless some special reason makes its post-
ponement desirable for him and not unfair to the offeror.” 21
Charles Alan Wright & Kenneth W. Graham, Jr., Federal
Practice and Procedure § 5037.1 (2d ed. 2005) (citing John
H. Wigmore, Code of Evidence 25 (3d ed. 1942)). The
requirement of timely and specific objections “serves to
ensure that the ‘nature of the error [is] called to the attention
of the judge, so as to alert him [or her] to the proper course
of action and enable opposing counsel to take corrective mea-
sures.’ ” United States v. Gomez-Norena, 908 F.2d 497, 500
(9th Cir. 1990) (quoting Advisory Committee’s Note to Rule
103(a), 56 F.R.D. 183, 195 (1972)) (first alteration in origi-
nal).

   [3] The specific basis for Defendant’s objection to Dr.
Gross’s testimony should have been asserted when Dr. Gross
testified as to Defendant’s compliance with his standard of

cier Electric Cooperative, Inc.: “We will review for plain or fundamental
error, absent a contemporaneous objection or motion for a new trial before
a jury has rendered its verdict, where the integrity or fundamental fairness
of the proceedings in the trial court is called into serious question.” 255
F.3d 1136, 1148 (9th Cir. 2001). Assuming, without deciding, that plain
error can ever be found under this standard as to jury instructions for
which objection was not given, the jury instruction given here without
objection does not meet our standard for plain error.
586                        JERDEN v. AMSTUTZ
care without reciting that he had knowledge of the proper
medical conduct within Defendant’s community.5 “An objec-
tion is ‘timely’ if it is made as soon as the opponent knows,
or should know, that the objection is applicable.” 1 Jack B.
Weinstein & Margaret A. Berger, Weinstein’s Federal Evi-
dence § 103.11 (Joseph M. McLaughlin ed., 2d ed. 1997)
(footnotes omitted); see also San Antonio Cmty. Hosp. v. So.
Cal. Dist. Council of Carpenters, 125 F.3d 1230, 1238 (9th
Cir. 1997) (concluding that the failure to raise a hearsay
objection until the close of direct examination is a waiver of
the objection); McKnight v. Johnson Controls, Inc., 36 F.3d
1396, 1408 (8th Cir. 1994); Belmont Indus. v. Bethlehem Steel
Corp., 512 F.2d 434, 437-38 (3d Cir. 1975).

   Despite the apparent delay and the lack of timeliness of the
Defendant’s specific objection at issue, we recognize that
“trial courts have broad discretion in making evidence rulings
and handling late objections.” Home Indem. Co. v. Lane Pow-
ell Moss & Miller, 43 F.3d 1322, 1329 (9th Cir. 1995); see
also United States v. Achiekwelu, 112 F.3d 747, 754 (4th Cir.
1997) (“Even when a district court admits evidence without
objection, the district court has the discretion to grant a subse-
quent motion made after the close of the evidence to exclude
the evidence.”). However, we hold here that the court’s late
exclusion of Dr. Gross’s testimony was an abuse of its discre-
tion because the untimely decision unfairly prevented Plain-
tiffs from providing a curative response.

   [3] We have adhered to the general rule that neither the dis-
trict court nor the opposing party may unfairly deprive parties
  5
   Because Defendant’s objection during Dr. Gross’s testimony did not
make any reference to the community where Defendant practiced, it did
not give the Plaintiffs fair notice of the grounds for Defendant’s successful
motion to strike Dr. Gross’s testimony made on May 28, near the end of
the trial. See United States v. Gomez-Norena, 908 F.2d 497, 500 (9th Cir.
1990) (holding that “a party fails to preserve an evidentiary issue for
appeal not only by failing to make a specific objection, but also by making
the wrong specific objection.”) (citations omitted) (emphasis in original).
                           JERDEN v. AMSTUTZ                           587
of the opportunity to lay a foundation in support of their evi-
dence. The opposing party may not delay objections until
after trial such that it becomes too late to resolve them effec-
tively. See Bartleson v. United States, 96 F.3d 1270, 1278
(9th Cir. 1996) (holding that an objection not raised during
trial is waived because the delay “denied [the witness] the
opportunity to lay a better foundation for his testimony, and
potentially denied the government the opportunity to intro-
duce other evidence on the issue”). Also, the district court
may not exclude evidence before trial without allowing the
parties to lay a foundation for its admission. See Wendt v.
Host International, Inc., 125 F.3d 806, 814 (9th Cir. 1997)
(holding that the district court abused its discretion in exclud-
ing evidence on summary judgment without providing the
parties with “the opportunity respectively to lay a foundation
for the admission of the survey or to challenge the adequacy
of the foundation”). Our prior decisions viewed together sup-
port the principle that an objection to admission of evidence
on foundational grounds must give the basis for objection in
a timely way to permit the possibility of cure.

   This principle is reinforced by decisions of other circuits
that have required district courts to give parties an opportunity
to respond to objections to the foundation of their evidence.
“Given the ‘liberal thrust’ of the federal rules it is particularly
important that the side trying to defend the admission of evi-
dence be given an adequate chance to do so.” Padillas v.
Stork-Gamco, Inc., 186 F.3d 412, 417 (3d Cir. 1999) (citation
omitted). “Counsel should not ‘sandbag’ Daubert concerns
until the close of an opponent’s case, thereby placing oppos-
ing counsel and the trial court at a severe disadvantage.”
Alfred v. Caterpillar, Inc., 262 F.3d 1083, 1087 (10th Cir.
2001).6
  6
    In contrast to this reasoning, the Fourth Circuit in United States v.
Achiekwelu sustained the granting of an untimely objection, which was
asserted after closing arguments, that defendant failed to provide authenti-
cation for a key document. 112 F.3d at 754. The court there held that Rule
103’s requirement of timely objections only applied to the appellate
court’s ability to review erroneous rulings, and did not limit the district
court’s discretionary power to grant these objections. Id.
588                         JERDEN v. AMSTUTZ
   [4] Considering our precedent and that of other circuits
interpreting Rule 103, we hold that the exclusion of testimony
for lack of foundation is improper following an untimely
objection if such objection unfairly deprives the proponents of
the testimony of an opportunity to cure the objection. Apply-
ing this rule here, we conclude that the district court did not
give Plaintiffs an opportunity to lay a foundation for the testi-
mony after the basis of Defendant’s objection to the existing
foundation was belatedly made clear. Any foundational flaw
in the testimony of Dr. Gross as presented likely could have
been fixed if Defendant had disclosed to Plaintiffs the basis
for his objection when Dr. Gross was still on the witness stand
and available to amplify his testimony.7

   [5] Defendant contended at oral argument that his objection
at the close of Plaintiffs’ evidence was timely because Plain-
tiffs failed to present an essential element of their case so that
the testimony was not improper until Plaintiffs closed their
case without providing the necessary predicate. However, we
reject this argument because Oregon case law describes the
foundation requirement as a rule of evidence, and not as an
element of defendant’s standard of care. See Creasey, 637
P.2d at 121 (stating that while the definition of Defendant’s
standard of care is a rule of law, “[t]he evidence question is
one of foundation or competency: Can an out-of-town expert
testify as to the propriety of a local practitioner’s treatment
   7
     The district court stated in its order denying Plaintiffs’ motion for a
new trial that Plaintiffs could have corrected the foundational flaw by
arranging for the witness to testify by telephone. Plaintiffs assert that this
option was not actually presented to them when the court considered the
motion to strike. Testimony in open court by telephone is permitted “for
good cause shown in compelling circumstances and upon appropriate safe-
guards,” Fed. R. Civ. P. 43(a). In light of the district court’s error in vali-
dating an untimely objection, it would be unfair to require Plaintiffs to
have initiated the option of a telephone deposition supplementing Dr.
Gross’s testimony given the short amount of time before the trial was set
to end and the relative disadvantage of having a key expert witness testify
by telephone.
                           JERDEN v. AMSTUTZ                           589
absent some knowledge of the standard of medical treatment
in the community?”). Therefore, the testimony of Dr. Gross
was immediately objectionable once Dr. Gross stated his
opinion on the standard of care if he had not satisfied all nec-
essary foundation for his opinion testimony.8

   [6] A timely and specific objection to Dr. Gross’s knowl-
edge of the standard of medical conduct in Defendant’s com-
munity would have allowed Plaintiffs to attempt to resolve the
foundational concern by asking Dr. Gross whether he had
knowledge of the proper standard for Defendant’s community
or a similar community. The district court should have given
Plaintiffs an opportunity to lay a proper foundation under the
locality rule, if they could do so, before the court decided to
grant Defendant’s untimely motion and to severely limit the
jury’s consideration of Dr. Gross’s testimony. By striking key
portions of Dr. Gross’s testimony that supported the negli-
gence claim, without providing Plaintiffs with an opportunity
to correct the foundational requirement of knowledge of local
medical standards, the district court abused its discretion.

                                    III

   Plaintiffs also assert error in the admission of Mr. Bowser’s
testimony concerning his observations of the MRA report,
which are a special type of MRI report. Mr. Bowser is a
neurosurgical nurse practitioner who acted as Defendant’s
surgical assistant during the operation on Mr. Jerden. He testi-
fied that he routinely reviewed imaging reports before opera-
tions although he was not licensed to interpret them.

   Plaintiffs examined Mr. Bowser as an adverse witness dur-
  8
    This conclusion is strengthened by considering the procedural context.
If Defendant had intended to argue in the district court that Plaintiffs had
failed to present evidence as to all elements of their claim, Defendant
might have tried to move for a directed verdict rather than for an instruc-
tion limiting portions of Dr. Gross’s testimony.
590                         JERDEN v. AMSTUTZ
ing their case-in-chief. During cross-examination, Defendant
asked Mr. Bowser about his observations of the MRA report
of Mr. Jerden and whether he thought that they indicated a
brain tumor. Defendant argues that Plaintiffs failed to make
a timely objection to this testimony. The transcript shows that
Plaintiffs’ counsel promptly and specifically objected when
these questions were raised by the Defendant but the objec-
tion was overruled by the court.9 The district court held that
these statements were admissible because Mr. Bowser was
testifying as a fact witness and did not state any opinions as
an expert.10

   [7] Lay witnesses can permissibly base opinion testimony
upon their experience, but the Federal Rules of Evidence
require that lay opinion testimony be “(a) rationally based on
the perception of the witness, (b) helpful to a clear under-
standing of the witness’ testimony or the determination of a
fact in issue, and (c) not based on scientific, technical, or
other specialized knowledge within the scope of Rule 702.”
Fed. R. Evid. 701. “The mere percipience of a witness to the
facts on which he wishes to tender an opinion does not trump
  9
    Defendant’s argument that Plaintiffs “opened the door” to this testi-
mony also fails because Plaintiffs never sought the opinion of Mr. Bowser.
“Under the rule of curative admissibility, or the ‘opening the door’ doc-
trine, the introduction of inadmissible evidence by one party allows an
opponent, in the court’s discretion, to introduce evidence on the same
issue to rebut any false impression that might have resulted from the ear-
lier admission.” United States v. Whitworth, 856 F.2d 1268, 1285 (9th Cir.
1988) (citation omitted). Plaintiffs questioned Mr. Bowser about the actual
diagnosis made before the surgery and how this diagnosis affected their
surgical procedure. The diagnosis and its effect on the surgery is a fact
independent of any personal opinion held by Mr. Bowser. Plaintiffs did
not attempt to introduce inadmissible expert opinion from these questions
such that Defendant would be permitted to follow them through the door.
   10
      In its order denying Plaintiffs’ motion for a new trial, the court upheld
its admission of Mr. Bowser’s testimony and its overruling of Plaintiffs’
objection by stating that the “trial transcript shows that Mr. Bowser did
not testify as an expert, and that he only testified as to what he did in his
practice, and specifically as to plaintiff Daniel Jerden’s care.”
                           JERDEN v. AMSTUTZ                             591
Rule 702.” United States v. Figueroa-Lopez, 125 F.3d 1241,
1246 (9th Cir. 1997) (holding that opinions were based on
specialized knowledge within the meaning of Rule 702
because they were “properly characterized as testimony based
on the perceptions, education, training, and experience of the
witness”).

   Mr. Bowser’s testimony contained detailed and scientific
observations about the MRA report and the conclusions that
he interpreted the MRA of Mr. Jerden’s brain to show signs
of a brain tumor. Mr. Bowser’s testimony did not merely
relate his factual observations of what occurred that was
within his competence to describe; instead, he rendered opin-
ions and inferences that he drew from his observations and
that, as he himself admitted, he was not competent to provide.

   [8] Because of its incorrect conclusion that Mr. Bowser was
simply testifying about facts, the district court did not use the
proper standards to determine whether the opinions expressed
by Mr. Bowser should have been characterized as expert or
lay opinions. If the district court wanted to consider Mr.
Bowser’s opinion as a lay opinion, then it was necessary to
assess all requirements of Federal Rule of Evidence 701: that
the opinion is rationally based on the witness’s perceptions,
that it is helpful to a trier of fact, and that it is not based on
scientific, technical or other specialized knowledge.11

  Plaintiffs are entitled to a thorough evaluation of Mr.
Bowser’s qualifications to interpret an MRA report as either
  11
     From the record before us now, Mr. Bowser’s statements that the
MRA report showed a brain tumor appear to be in the nature of proffered
expert opinions based on his experience as a nurse practitioner working in
neurosurgery. If Mr. Bowser lacked the specialized experience to state
these opinions as an expert consistent with Federal Rule of Evidence 702,
then the record before us does not indicate that his opinions would likely
be admissible as lay opinion testimony because the record does not dis-
close a rational basis in his perceptions or a legitimate capacity to help the
trier of fact with lay opinion.
592                    JERDEN v. AMSTUTZ
a qualified expert or as a lay witness entitled to give opinion,
in light of the division in the testimonial opinions that were
given by undisputedly qualified experts. See Figueroa-Lopez,
125 F.3d at 1246 (“Trial courts must ensure that experts are
qualified to render their opinions and that the opinions will
assist the trier of fact.”). While the privileges granted to Mr.
Bowser by the state licensing board are not dispositive of his
right to testify, he must show greater expertise in the field
before he can be deemed qualified to opine on the compli-
cated and divisive issue of this MRA report. On the current
record, we are skeptical that he meets this standard.

  [9] We conclude that it was error to permit Mr. Bowser to
give opinion testimony interpreting the MRA report as show-
ing a tumor when there was no testimony showing that he was
qualified as an expert to do so, within the scope of Federal
Rule of Evidence 702, or otherwise permitted to give lay
opinion testimony consistent with the standards of Federal
Rule of Evidence 701.

                               IV

   Although we have concluded that the district court erred in
striking and limiting the testimony of Dr. Gross in light of the
untimely specificity of the objection, and that the district court
also erred in admitting Mr. Bowser’s testimony on the same
issue, these conclusions do not end our inquiry.

   [10] Evidentiary errors to warrant reversal must affect the
substantial rights of the appellant. Obrey v. Johnson, 400 F.3d
691, 699 (9th Cir. 2005) (citing Fed. R. of Evid. 103 and Fed.
R. Civ. P. 61). However, we start with “a presumption of prej-
udice.” Id. at 701. As pertinent here, that presumption may be
rebutted if Defendant can show that, more likely than not, the
jury would have reached the same verdict if Dr. Gross’s testi-
mony had been admitted on negligence and Mr. Bowser’s tes-
timony interpreting the MRA report had been excluded.
                          JERDEN v. AMSTUTZ                          593
   [11] We are considering these errors cumulatively. See,
e.g., Gonzales v. Police Dept., City of San Jose, Cal., 901
F.2d 758, 762 (9th Cir. 1990) (“Considered together, there is
no doubt that a remand is required in light of the cumulative
effect of the two material errors.”); Gordon Mailloux Enters.,
Inc. v. Firemen’s Ins. Co. of Newark, N.J., 366 F.2d 740, 742
(9th Cir. 1966) (“We conclude it too must be reversed;
although the errors requiring reversal, if considered sepa-
rately, were perhaps harmless, their cumulative effect was
prejudicial.”). Many of our sister circuits have similarly held
that cumulative error in a civil trial may suffice to warrant a
new trial even if each error standing alone may not be prejudi-
cial. See, e.g., Beck v. Haik, 377 F.3d 624, 645 (6th Cir. 2004)
(“Since a jury reaches its verdict in light of the evidence as
a whole, it makes no sense to try to analyze errors in artificial
isolation, when deciding whether they were harmless.”);
Frymire-Brinati v. KPMG Peat Marwick, 2 F.3d 183, 188
(7th Cir. 1993); Malek v. Fed. Ins. Co., 994 F.2d 49, 55 (2d
Cir. 1993); Hendler v. United States, 952 F.2d 1364, 1383
(Fed. Cir. 1991); but see SEC v. Infinity Group Co., 212 F.3d
180, 196 (3d Cir. 2000).

   [12] This case involved multiple medical experts on both
sides testifying as to the proper interpretation of the MRI and
MRA reports and whether Defendant’s mistaken interpreta-
tion of the reports as showing a tumor, rather than demyelin-
ation, was a breach of his standard of care. The jury was
required to decide which side to believe, assessing credibility
of witnesses and determining how much weight to give the
views of each. We cannot say that “it is more probable than
not that the jury would have reached the same verdict” if Dr.
Gross’s testimony had not been limited and if Mr. Bowser’s
testimony had been. Obrey, 400 F.3d at 701. We conclude
that the errors affected a substantial right of the parties and
constituted reversible error warranting a new trial.12 We
   12
      Because we reverse on these evidentiary errors, we need not consider
Plaintiffs’ further argument that a new trial was warranted because of
Plaintiffs’ counsel’s belated discovery that Defendant Amstutz had a pros-
thetic eye.
594                  JERDEN v. AMSTUTZ
accordingly reverse the district court’s judgment and remand
for further proceedings consistent with this disposition.

  REVERSED AND REMANDED.
