Maloney v. DeRoberts: Expert Disclosure, Witness Management, and Negligent Spoliation in New York Medical Malpractice Trials

I. Introduction

The Appellate Division, Fourth Department’s decision in Maloney v. DeRoberts, 2025 NY Slip Op 06411 (4th Dept 2025), is a medical malpractice appeal that, while affirming a defense verdict, provides a dense cluster of trial-practice guidance. The opinion does not announce a single dramatic new rule; instead, it consolidates and clarifies several important doctrines that shape how medical malpractice trials are conducted in New York:

The permissible breadth of expert trial testimony under CPLR 3101(d) disclosures.
When expert disclosure is (and is not) required, especially for factual matters.
The limits of rebuttal evidence and the consequences of failing to disclose fact witnesses.
The timing and extent of required disclosure of expert witness identity in medical malpractice actions.
Preservation of objections to attorney misconduct for appellate review.
The standards for imposing an adverse inference jury instruction based on negligent spoliation of electronic evidence (a cell phone containing a critical voicemail).

The plaintiffs, Robert and Marilyn Maloney, alleged that defendants—a plastic surgeon, a nurse practitioner, and their practice—committed malpractice by failing to timely diagnose melanoma from a 2018 biopsy of a left-shin lesion, which was reported as benign. A voicemail from defendants’ office allegedly reassured Mr. Maloney that there was “nothing to worry about.” He did not return for follow-up and never went back to the practice. In 2019, a different practice biopsied another lesion on the same shin, which proved to be malignant melanoma.

After a jury returned a defense verdict, plaintiffs appealed, claiming they were denied a fair trial by multiple erroneous evidentiary and procedural rulings. The Fourth Department unanimously affirmed, using established appellate principles about trial court discretion and harmless error to reject each challenge. In doing so, the court offered important clarifications about expert-related disclosures, witness management, and spoliation.

II. Summary of the Opinion

The Fourth Department affirmed the judgment entered on a jury verdict in favor of the defendants in this medical malpractice action. The court held, in substance:

Expert disclosure and pathology testimony: Defendants’ expert was properly allowed to testify that the 2019 cancerous lesion was pathologically different from the 2018 lesion, because that opinion was within the scope of defendants’ CPLR 3101(d) expert disclosure, which had broadly indicated that the expert would opine on the pathology slides and distinguish the 2018 “blue nevus” from melanoma.
No expert disclosure required for factual testimony on lesion location: Defendants’ expert could testify about the physical locations of the lesions on the leg without specific expert disclosure, because location was a factual matter not requiring expert opinion.
Limits on rebuttal evidence: Plaintiffs were properly precluded from introducing “rebuttal” evidence to counter the expert’s testimony on lesion location; plaintiffs had already introduced location evidence in their direct case, and defendants offered nothing new on that point that required true rebuttal.
Preclusion of undisclosed former employee witness: The trial court acted within its discretion in precluding plaintiffs from calling a former employee of defendants—never previously disclosed on any witness list—both in their case-in-chief and as rebuttal, to avoid unfair surprise and because her testimony about old office practices was only marginally relevant.
Disclosure of expert identity at trial: Although CPLR 3101(d)(1)(i) permits a party in a medical malpractice case to omit an expert’s name from pretrial disclosures, the trial court may require disclosure of the expert’s identity at trial; ordering plaintiffs to disclose their expert’s name shortly before he took the stand was not an abuse of discretion.
Alleged improper comments by defense counsel: Most of plaintiffs’ complaints about counsel’s comments were unpreserved for appellate review due to lack of contemporaneous objection or failure to seek additional relief beyond an admonition.
Adverse inference instruction for spoliation of the cell phone: The court properly gave an adverse inference instruction based on plaintiffs’ failure to preserve the cell phone that contained the key voicemail from defendants’ practice. The court correctly explained that a “culpable state of mind” for spoliation purposes includes negligence, where a party discards relevant evidence after it reasonably should anticipate litigation.
Harmless error and remaining issues: Any other alleged errors did not warrant reversal under CPLR 2002’s harmless error rule.

Taken together, the opinion reinforces deference to trial judges in evidentiary matters and underscores litigants’ obligations to manage discovery, witnesses, and evidence preservation carefully.

III. Detailed Analysis

A. Trial Court Discretion and Harmless Error Framework

The opinion begins by situating the appeal within the standard framework for reviewing evidentiary rulings:

Broad discretion: The court cites Mazella v Beals, 27 NY3d 694, 709 (2016), and People v Carroll, 95 NY2d 375, 385 (2000), reaffirming that trial courts are accorded “wide discretion” in evidentiary decisions and that such rulings should not be disturbed absent abuse of discretion.
Relevance and prejudice: Evidence must be relevant, and its probative value must outweigh the risk of undue prejudice (Mazella, 27 NY3d at 709; Richardson on Evidence §4-101).
Harmless error: CPLR 2002 provides that an error in a ruling “shall be disregarded if a substantial right of a party is not prejudiced.” The court cites Mazella, 27 NY3d at 711, and Senycia v Vosseler, 217 AD3d 1520, 1522 (4th Dept 2023), reinforcing that not every misstep at trial (even if erroneous) mandates reversal.

This framework is crucial: it sets a high threshold for plaintiffs to overturn a defense verdict based on trial-management complaints. The appellate court’s approach is consistently to ask not only “Was the ruling arguably debatable?” but “Did it reflect an abuse of discretion that prejudiced a substantial right?”

B. Expert Disclosure and Trial Testimony

1. Scope of Expert Disclosure: Pathology Opinions

A central dispute concerned defendants’ expert pathologist, who testified that the 2019 melanoma lesion was pathologically different from the 2018 lesion. Plaintiffs argued that this “new theory” exceeded the scope of defendants’ CPLR 3101(d) disclosure and should have been precluded.

The Fourth Department rejected this, focusing on the content of the disclosure:

The disclosure stated the expert would “offer opinions regarding the pathological analysis of the pathology slides in this case.”
It specifically noted the 2018 shin lesion “appears to be a blue nevus,” and that this “differs pathologically from a melanoma.”
It indicated that the expert would respond to plaintiffs’ experts.

On that basis, the court held that defendants’ expert “would provide precisely the type of pathological testimony that plaintiffs challenged.” The challenged testimony—that the 2018 and 2019 lesions were pathologically different—was therefore “encompassed by their expert disclosure.”

The court cited:

Neumire v Kraft Foods, 291 AD2d 784, 786 (4th Dept 2002), lv denied 98 NY2d 613 (2002) – allowing reasonably related expert testimony where adequately foreshadowed.
Saraiva v New York State Thruway Auth., 234 AD3d 1325, 1327 (4th Dept 2025), lv denied 44 NY3d 904 (2025) (cf.) – illustrating when testimony may exceed a disclosure’s scope.
Mazella v Beals, 27 NY3d 694 (2016) – endorsing a flexible, non-hypertechnical approach to expert disclosure, focusing on fair notice rather than rigid precision.

The principle that emerges is:

If an expert disclosure clearly signals the subject matter, type of opinions, and core distinctions the expert will draw (e.g., benign versus malignant pathology; nature of a lesion on particular slides), the expert may testify in detail at trial on those matters—even if the precise formulations or nuances are not fully spelled out in the disclosure.

This reinforces a pragmatic, notice-based approach to CPLR 3101(d): as long as the adversary is not unfairly surprised, courts will not treat detailed trial elaboration as an undisclosed “new theory.”

2. No Expert Disclosure Required for Purely Factual Points

Plaintiffs also claimed that defense expert testimony concerning the location of the lesions exceeded the disclosure’s scope. The court disposed of this contention differently, by characterizing lesion location as a factual matter that did not require expert opinion:

“[N]o expert disclosure was required on that point inasmuch as it was a question of fact that did not require an expert opinion to establish.”

The court grounded this in:

Havas v Victory Paper Stock Co., 49 NY2d 381, 386 (1980) – recognizing distinctions between factual and expert testimony.
O’Neill v Pelusio, 65 AD2d 914, 914–915 (4th Dept 1978) – similar recognition that certain observations are lay/factual, not expert opinion.

This is doctrinally significant for practice:

An expert witness may testify to factual observations (e.g., where a lesion was located on the body) without that aspect needing to be previewed in CPLR 3101(d) expert disclosure.
What triggers CPLR 3101(d) is the giving of opinion testimony—specialized, technical interpretation—not every factual statement that happens to come from an expert.

For litigators, this underscores the need to distinguish between:

Opinions that must be disclosed in CPLR 3101(d) (e.g., causation, standard of care, differential diagnosis, pathological characterization); and
Basic facts that any witness, including an expert, may testify about (e.g., physical placement, whether a document was reviewed, sequence of events), which generally do not require expert disclosure.

C. Rebuttal Evidence: What It Is—and Is Not

Plaintiffs argued that they should have been allowed to introduce evidence rebutting defense expert testimony about the locations of the 2018 and 2019 lesions, seeking to show they were the same lesion.

The Fourth Department, relying on classic New York law on rebuttal evidence, rejected that claim.

The court quoted Marshall v Davies, 78 NY 414, 420 (1879), defining rebuttal as:
“not merely evidence which contradicts the witnesses on the opposite side and corroborates those of the party who began, but evidence in denial of some affirmative fact which the answering party has endeavored to prove.”
It also cited People v Harris, 98 NY2d 452, 489 (2002), and Yeomans v Warren, 87 AD2d 713 (3d Dept 1982), reiterating that rebuttal is a targeted response to a new affirmative claim by the opposing party.
The court noted that plaintiffs had already introduced evidence about lesion location in their direct case; defendants did not inject a new, previously unaddressed issue.
Thus, there was “no basis for plaintiffs to rebut” the assertion that, based on their respective locations, the 2018 and 2019 lesions were different, because defendants “introduced no evidence on that question that plaintiffs had not already addressed.”
The court referenced Hutchinson v Shaheen, 55 AD2d 833, 834 (4th Dept 1976), and Syracuse Airport Metroplex v City of Syracuse, 249 AD2d 926, 927 (4th Dept 1998), cementing the rule that a party cannot re-open its own case-in-chief under the guise of “rebuttal.”

The practical lesson:

Rebuttal is not a second bite at the apple. If an issue is part of your main theory (e.g., whether two lesions are the same), you must present your full proof of it in your direct case. You cannot hold back and hope to use rebuttal to cure omissions or strengthen weak proof.
Trial judges have discretion to curtail rebuttal to its proper function—responding to new or affirmative factual assertions from the defense.

D. Preclusion of Undisclosed Fact Witnesses (Former Employee)

Another dispute involved plaintiffs’ attempt to call one of defendants’ former employees as a witness in their direct case without having disclosed her on any witness list.

The Fourth Department first confirmed that although “nothing in CPLR article 31 requires a party to generate a witness list per se,” a court may, in its discretion, require disclosure of witnesses. It cited:

Hunter v Tryzbinski, 278 AD2d 844, 844–845 (4th Dept 2000);
22 NYCRR 202.37 (trial readiness and pretrial conference rule, including witness disclosure obligations).

The court noted that discovery’s purpose includes preventing “gamesmanship and unfair surprise at trial.” It was undisputed that plaintiffs had never disclosed the former employee as a witness. The trial court found that calling her would prejudice defendants, and the Appellate Division refused to second-guess that discretionary determination.

The ruling is supported by:

Gerasimowicz v Delis, 231 AD3d 536, 537 (1st Dept 2024);
Eros Intl. PLC v Mangrove Partners, 191 AD3d 464, 465 (1st Dept 2021);
Slomczewski v Ross, 148 AD3d 1648, 1649 (4th Dept 2017).

The court also upheld preclusion of the former employee as a rebuttal witness:

Plaintiffs sought to use her to testify about defendants’ office practices.
Defendants had offered no specific testimony on office practices that required rebuttal within the meaning of Marshall v Davies; thus, her testimony was not proper rebuttal.
Moreover, her testimony related to office practices “years before the alleged negligence occurred,” casting doubt on its relevance.

Practical implications:

Parties must timely disclose potential fact witnesses identified in pretrial orders or demanded witness lists; failure can lead to preclusion.
Courts will focus on prejudice and surprise: using an undisclosed witness at trial, especially someone closely connected to the opposing side (like a former employee), is vulnerable to preclusion.
Attempting to relabel such a witness as “rebuttal” will not succeed if the testimony does not truly address a new affirmative point raised by the other side at trial.

E. Identity of Medical Experts Under CPLR 3101(d)(1)(i)

New York’s CPLR 3101(d)(1)(i) creates a special rule for expert disclosure in medical malpractice actions: parties may omit the expert’s name from their disclosure. This is meant to protect medical professionals from pressure or retaliation by colleagues.

Plaintiffs argued that the trial court erred in compelling them to disclose their expert’s identity shortly before he testified. The Fourth Department rejected this, clarifying the temporal reach of the anonymity protection:

The court relied on Thomas v Alleyne, 302 AD2d 36, 45 (2d Dept 2002), and Mercado v Schwartz, 209 AD3d 30, 38 (2d Dept 2022), emphasizing that the omission of the expert’s name “postpone[s] revelation” only “until the time of trial.”
It also cited Rivera v Albany Med. Ctr. Hosp., 119 AD3d 1135, 1137 n 1 (3d Dept 2014), in support of this timing limitation.

The court held that requiring plaintiffs to disclose their expert’s name shortly before he took the stand— essentially at the point of examination—was within the trial court’s discretion.

The practical rule:

In a medical malpractice case, a party may keep an expert’s identity anonymous during pretrial discovery, but cannot insist on perpetual anonymity through trial. Once the expert is about to testify, the trial judge may require disclosure of the expert’s name, and doing so is not an abuse of discretion.

This is important for planning witness security, scheduling, and cross-examination preparation. Opposing counsel can expect to learn the expert’s identity at least when the expert is called to the stand— and litigants relying on anonymity should not assume they can withhold the name throughout the trial.

F. Attorney Misconduct and Preservation of Objections

Plaintiffs claimed they were denied a fair trial by improper comments by defense counsel. The Fourth Department treated this, as is typical, as a preservation problem.

Many of the challenged comments drew no contemporaneous objection; such issues are unpreserved for appeal (Masmalaj v New York City Economic Dev. Corp., 197 AD3d 1294, 1296 (2d Dept 2021); Baynes v Maple 3, LLC, 169 AD3d 749, 750 (2d Dept 2019); Lagos v Fucale, 139 AD3d 908, 908 (2d Dept 2016), lv dismissed 28 NY3d 1178 (2017)).
On at least one occasion plaintiffs did object and obtained an admonition from the court, but they did not seek further relief (such as a mistrial) after the admonition. This rendered that portion of their complaint unpreserved as well (Country Park Child Care, Inc. v Smartdesign Architecture PLLC, 129 AD3d 1636, 1637 (4th Dept 2015); Lucian v Schwartz, 55 AD3d 687, 688–689 (2d Dept 2008), lv denied 12 NY3d 703 (2009)).

Key takeaways:

To preserve a complaint about counsel’s improper comments, a party must:
- Object contemporaneously;
- Seek appropriate corrective action; and
- If the correction is inadequate, request further relief (e.g., mistrial, curative instruction).
Failure to complete this sequence generally forfeits the issue on appeal, absent the very rare invocation of “interest of justice” review (which the court did not apply here).

G. Spoliation and Adverse Inference Instruction for a Discarded Cell Phone

Perhaps the most practically important aspect of Maloney is its application of New York’s spoliation doctrine to modern electronic evidence—a cell phone containing a key voicemail. This is where the opinion most clearly reinforces (and to some degree sharpens) the rule that negligence can constitute a “culpable state of mind” sufficient to justify an adverse inference instruction.

1. The Facts on Spoliation

The voicemail from defendants’ practice conveyed the 2018 biopsy results. Plaintiffs claimed it was “reassuring” and communicated there was “nothing to worry about”—a central fact for their theory that defendants downplayed the risk and failed to follow up. However:

Mr. Maloney did not preserve the phone that contained the voicemail.
The exact language of the voicemail was thus unknown at trial.
Plaintiffs admitted discarding the phone at a time when they should have reasonably anticipated litigation regarding defendants’ treatment.

The trial court granted defendants’ request for an adverse inference jury instruction based on spoliation. The instruction told the jury that plaintiffs had a “culpable state of mind” in failing to preserve the phone. To soften any implication of intentional wrongdoing, the court defined “culpable” as including negligence.

2. The Legal Standard for Spoliation

The Fourth Department framed its analysis using the Court of Appeals’ seminal decision in Pegasus Aviation I, Inc. v Varig Logistica S.A., 26 NY3d 543 (2015), and its own recent decision in Storm v Kaleida Health, 229 AD3d 1239 (4th Dept 2024).

Under New York law, to justify a spoliation sanction (including an adverse inference), the moving party must show:

The spoliating party had control over the evidence.
At the time of destruction or loss, that party had an obligation to preserve the evidence because it reasonably should have anticipated litigation.
The evidence was relevant to a claim or defense.
The spoliating party acted with a culpable state of mind in losing or destroying the evidence.

Crucially, as Pegasus held and Maloney reiterates, the culpable state of mind requirement does not require bad faith or intentional destruction:

The “culpable state of mind” needed to support a sanction for spoliation includes negligence in cases where the above elements are met.

The court also cited Mahiques v County of Niagara, 137 AD3d 1649, 1652 (4th Dept 2016), and Page v Niagara Falls Mem. Med. Ctr., 167 AD3d 1428, 1430 (4th Dept 2018), for similar applications of negligent spoliation principles, and Storm, 229 AD3d at 1240–1241, emphasizing the trial court’s “broad discretion” in fashioning spoliation remedies.

3. Application to the Voicemail and Phone

Applying these principles, the Fourth Department held:

Plaintiffs admitted that they failed to retain the phone containing the voicemail at a time when they should have reasonably anticipated litigation regarding defendants’ treatment—meeting the duty-to-preserve and “culpable state of mind” (negligence) requirements.
The voicemail was clearly relevant to plaintiffs’ claims, as it bore on what information plaintiffs received about the 2018 biopsy and what instructions (if any) they were given regarding follow-up.
The trial court’s choice of an adverse inference instruction—rather than a more draconian sanction— was a measured exercise of its broad discretion.

The court also highlighted that the trial judge carefully defined “culpable” to mean negligent, specifically to avoid unfairly suggesting that plaintiffs intentionally destroyed the evidence.

4. Practical Impact

For litigants, especially in medical malpractice and other fact-intensive cases, this part of Maloney delivers several concrete warnings:

Electronic evidence must be preserved. Clients must be told early and clearly to keep phones, texts, emails, and voicemails related to treatment or the dispute once litigation is reasonably foreseeable.
Negligent loss is enough. Even if a party did not intend to harm the opponent’s case, casually discarding or replacing a device that contains critical evidence may expose that party to an adverse inference.
Adverse inference is a powerful sanction. The jury may be told it can infer that the missing evidence would have been unfavorable to the party who failed to preserve it—potentially shifting the factual narrative in a close case.

In malpractice contexts specifically, where communications about test results and follow-up instructions are often disputed, Maloney underscores that losing a phone or message after litigation becomes reasonably foreseeable can materially weaken a plaintiff’s position.

IV. Complex Concepts Simplified

Below are brief, plain-language explanations of key legal concepts appearing in the opinion.

1. Medical Malpractice

Medical malpractice arises when a healthcare provider deviates from accepted medical practice (the “standard of care”) and that deviation causes injury to a patient. A plaintiff typically must prove:

Applicable standard of care;
Deviation from that standard (negligence);
Causation (that the deviation caused the harm); and
Damages.

Expert medical testimony is usually required to establish the standard of care and causation.

2. Expert Disclosure (CPLR 3101(d)(1)(i))

In New York, expert disclosure is the process by which a party informs the opponent, before trial, about the substance of its experts’ opinions. Under CPLR 3101(d)(1)(i):

A party must disclose:
- The subject matter on which the expert is expected to testify;
- The substance of the facts and opinions on which the expert is expected to testify; and
- A summary of the grounds for each opinion.
In a medical malpractice case, the expert’s name may be omitted in the disclosure, but only to delay disclosure of identity until trial, not to keep it secret indefinitely.

3. Rebuttal Evidence

Rebuttal evidence is evidence introduced after the opponent’s case to respond to new, affirmative facts the opponent has put forward. It is not:

A chance to fix weaknesses in one’s own earlier case; or
A way to re-present or bolster evidence already offered in chief.

Proper rebuttal denies or explains new assertions introduced by the other side.

4. Spoliation of Evidence

“Spoliation” means the destruction or significant loss of evidence that is relevant to a legal dispute. A party may be sanctioned if:

The party had control of the evidence;
The party had a duty to preserve it (because litigation was reasonably foreseeable);
The evidence was relevant; and
The evidence was destroyed or lost with a culpable state of mind (which can include negligence).

Sanctions range from monetary penalties, to adverse inference instructions, to, in extreme cases, striking pleadings.

5. Adverse Inference Instruction

An adverse inference instruction is a direction from the judge to the jury that it may (but need not) conclude that missing or destroyed evidence would have been unfavorable to the party responsible for its loss. It is a middle-ground spoliation sanction:

It does not decide the case automatically;
But it allows the jury to draw a negative inference, potentially tipping the fact-finding balance.

6. “Culpable State of Mind”

In the context of spoliation, “culpable state of mind” does not require fraud or intentional destruction. Under New York law, it can include:

Intentional destruction;
Recklessness; or
Negligence: failing to take reasonable care to preserve evidence when litigation is foreseeable.

Maloney emphasizes that negligent loss of a phone containing a key voicemail, when litigation is reasonably anticipated, qualifies as culpable.

7. Harmless Error (CPLR 2002)

CPLR 2002 states that a judgment should not be reversed because of an error that does not affect a substantial right of a party. In practical terms:

Even if a trial judge makes a mistake (for example, in admitting or excluding evidence), an appellate court will not disturb the verdict unless the error likely influenced the outcome or prejudiced a significant legal interest.

8. Preservation of Error

To raise a trial error on appeal, a party usually must have:

Objected promptly when the error occurred;
Stated the grounds for the objection; and
Sought appropriate relief if the initial remedy (e.g., an admonition) was insufficient.

Failing to do so generally means the appellate court will decline to consider the complaint.

V. Impact and Broader Significance

While Maloney v. DeRoberts does not revolutionize New York law, it meaningfully consolidates several practical rules for medical malpractice and other civil trials:

Expert practice: The case confirms a flexible approach to CPLR 3101(d): reasonably detailed disclosures that clearly define subject matter and core opinions will support richer, more nuanced expert trial testimony. At the same time, it draws a line between expert “opinions” and basic facts—only the former must be disclosed as expert material.
Trial structure and rebuttal: Trial lawyers cannot rely on rebuttal to fix omissions in their main proof. Maloney will help trial judges sustain rulings that limit rebuttal to addressing genuinely new issues.
Witness management and disclosure: The decision reiterates that undisclosed witnesses may be precluded at trial to avoid unfair surprise, particularly former employees of an opposing party. It gives further support to trial courts enforcing pretrial witness-disclosure orders under 22 NYCRR 202.37.
Expert identity in med-mal cases: The opinion harmonizes CPLR 3101(d)(1)(i)’s anonymity protection with trial management needs, confirming that anonymity is temporary and that trial judges may require disclosure of experts’ names when they take the stand.
Electronic evidence and spoliation: The case offers a concrete, modern illustration that negligent loss of a cell phone containing a critical voicemail can support an adverse inference. This will likely encourage both plaintiffs and defendants to implement more robust evidence-preservation practices once litigation is anticipated.
Appellate review culture: By repeatedly emphasizing trial court discretion and harmless error, the decision reinforces a deferential standard of appellate review in evidentiary matters, signaling that only clearly prejudicial misuses of discretion will lead to reversal of a jury verdict.

For practitioners, Maloney is thus less about changing the law than about clarifying how several strands of doctrine—expert disclosure, rebuttal, witness preclusion, expert anonymity, and spoliation—fit together in a realistic trial setting.

VI. Conclusion

Maloney v. DeRoberts affirms a defense verdict in a melanoma misdiagnosis case but does far more than resolve a single dispute. It synthesizes and applies key principles governing:

The permissible scope of expert testimony under CPLR 3101(d) disclosures;
The distinction between expert opinions and factual testimony requiring no expert disclosure;
The proper limits of rebuttal evidence;
The consequences of failing to disclose witnesses in advance of trial;
The timing of expert identity disclosure in medical malpractice cases; and
The standards and consequences of negligent spoliation, especially of electronic evidence like cell phones and voicemails.

By upholding each of the trial court’s challenged rulings, the Fourth Department underscores the strong discretion vested in trial judges and the centrality of fairness and predictability in trial management. The opinion will serve as a useful reference point for New York litigators navigating expert disclosures, witness lists, rebuttal strategy, and evidence preservation in medical malpractice and other complex civil litigation.