Rule 37 Exclusion for Untimely Expert Reports: Related Litigation Does Not Revive Expired Scheduling Deadlines

Introduction

In Lakeview Pharmacy of Racine, Inc. v. Catamaran Corporation (3d Cir. Mar. 9, 2026) (not precedential), the Third Circuit affirmed a district court’s exclusion of a plaintiff’s damages expert report served years after the court-ordered deadline, and the resulting grant of summary judgment for the defendant. The dispute arose from a 2015 breach of contract action filed by Lakeview Pharmacy of Racine, Inc. (“Lakeview”) against Catamaran Corporation (“Catamaran”).

The central issues on appeal were whether Lakeview’s late expert disclosure was “substantially justified” or “harmless” under Federal Rule of Civil Procedure 37(c)(1), and whether the district court abused its discretion when, applying Third Circuit factors, it excluded the report—effectively ending the case because Lakeview conceded the report was its only proof of damages.

A recurring practical question framed the case: can expert work developed and litigated in a later, separate action (here, Mabe v. Optum Rx) serve as a de facto substitute for meeting deadlines in an earlier action—especially after a court has denied consolidation? The Third Circuit’s answer was no.

Summary of the Opinion

The Third Circuit held that the district court acted within its discretion in excluding Lakeview’s expert report because:

  • Lakeview violated the operative scheduling order by serving the expert report nearly four years late.
  • Lakeview further violated Rule 26 by failing to disclose the “facts or data” considered by its experts until a week before summary-judgment argument.
  • Lakeview never moved for an extension of expert deadlines under Rule 16(b)(4), despite the scheduling order’s “good cause” requirement.
  • Applying the exclusion factors from Konstantopoulos v. Westvaco Corp. (quoting Meyers v. Pennypack Woods Home Ownership Ass'n), the district court permissibly found prejudice, lack of cure, disruption, and willfulness.

Because Lakeview conceded the excluded report was its only damages evidence, the Third Circuit affirmed summary judgment for Catamaran.

Analysis

Precedents Cited

Konstantopoulos v. Westvaco Corp. and Semper v. Santos: Deference to Trial Courts Enforcing Pretrial Orders

The panel anchored its standard of review in Konstantopoulos v. Westvaco Corp., which (quoting Semper v. Santos) emphasizes that an appellate court will not disturb exclusion of evidence for violating a pretrial order absent a “clear abuse of discretion.” This framing matters: once the dispute is cast as case-management enforcement rather than a close evidentiary call, the district court’s discretion becomes the dominant consideration.

Meyers v. Pennypack Woods Home Ownership Ass'n: The Exclusion-Factor Framework

The opinion applied the familiar factors (as restated in Konstantopoulos quoting Meyers): (1) prejudice or surprise; (2) ability to cure; (3) disruption; and (4) bad faith or willfulness—along with consideration of the importance of the evidence. The court treated these factors as a structured way to evaluate whether Rule 37(c)(1)’s automatic exclusion (“not allowed to use”) should apply.

In re Paoli R.R. Yard PCB Litig.: “Broad Leeway” to Manage Cases

Citing In re Paoli R.R. Yard PCB Litig., the panel reinforced a policy rationale: trial courts need “broad leeway to manage” their dockets, and exclusionary sanctions—though harsh—are often upheld to preserve the integrity of scheduling and disclosure regimes.

ZF Meritor, LLC v. Eaton Corp.: When Late Expert Materials May Be Non-Disruptive

Lakeview attempted to minimize disruption. The panel distinguished a scenario referenced in ZF Meritor, LLC v. Eaton Corp., where allowing alternate damages calculations caused little disruption because the court and parties expected liability to be decided before a damages trial schedule was set. Here, by contrast, admitting the report would require reopening and resetting discovery “at this late stage of litigation,” after summary judgment motion practice.

Out-of-Circuit Authorities Rejected as “Inapposite”

The court explicitly rejected Lakeview’s reliance on: 103 Investors I, L.P. v. Square D Co., Sherrod v. Lingle, and OPS Fitel, LLC v. Epstein. Those cases involved circumstances such as failure to grant parallel extensions, partial justification tied to scheduling mechanics, or repeated advance notice that discovery delays would delay expert work. The Third Circuit found those rationales absent here, emphasizing Lakeview neither sought extensions nor provided a comparable procedural predicate that would convert delay into “substantial justification.”

Mabe v. Optum Rx: Separate Litigation Does Not “Cure” Deadlines in This Case

Although the expert report was served in connection with Mabe v. Optum Rx and Optum had deposed the expert and served rebuttal reports there, the panel treated that history as legally insufficient to cure prejudice in Lakeview. Two facts were decisive: the district court had denied consolidation due to “divergent procedural postures and claims,” and the Mabe rebuttal work was not taken “in Lakeview.” The panel thus rejected the idea that cross-captioning an expert report or litigating it in another case provides functional notice or compliance in a different case with expired deadlines.

Legal Reasoning

1) Rule 16(b)(4): Scheduling Orders Remain Operative Until Modified

The court treated the original scheduling order as controlling because it was never amended. Under Rule 16(b)(4), schedules “may be modified only for good cause and with the judge’s consent.” Discovery disputes and judicial delay did not, by themselves, rewrite the expert deadline—especially where Lakeview never moved to extend it. The opinion underscores a practical rule: even when litigation stalls, parties must seek relief through motions to modify deadlines, not by unilateral late service.

2) Rule 26(a)(2): Expert Reports Must Include Supporting “Facts or Data”

Beyond lateness, the panel emphasized an independent disclosure failure: Rule 26(a)(2)(B)(ii) requires that an expert report be accompanied by “the facts or data considered.” Lakeview waited until a week before summary-judgment argument to disclose the materials allegedly used—four years after serving the report. The court characterized Rule 26 disclosures as “self-executing,” rejecting any suggestion that Catamaran’s failure to request the material earlier excused Lakeview’s noncompliance.

3) Rule 37(c)(1) and the Pennypack/Konstantopoulos Factors: Exclusion Was Within Discretion

The panel accepted the district court’s factor-by-factor conclusions:

  • Prejudice: Requiring additional discovery and motion practice (including potential Daubert litigation) nearly a decade after deadlines, and after summary judgment motions, was inherently burdensome and costly—prejudice that does not depend on an imminent trial date.
  • Ability to cure: Prior depositions and rebuttal reports in Mabe did not cure prejudice in Lakeview, given the denial of consolidation, different captions in key materials, and the absence of a Lakeview-specific discovery track.
  • Disruption: Admission would require resetting discovery and case management at a very late stage, disrupting orderly resolution even without a scheduled trial date.
  • Willfulness: Willfulness was supported by Lakeview’s failure to request deadline extensions and its prolonged noncompliance with Rule 26’s “facts or data” requirement. The court read a later order requesting “future case management” as not reopening discovery.

The opinion also notes, implicitly, that the “importance” factor cut in Lakeview’s favor (the report was critical), but that importance does not override prolonged, unjustified noncompliance—particularly when the noncompliant party made the evidence indispensable by failing to develop alternative proofs.

Impact

  • Reinforces the “deadlines are real” principle: Even extended periods of procedural stagnation do not suspend expert deadlines. Parties must proactively move under Rule 16(b)(4).
  • Limits reliance on parallel litigation: Expert discovery conducted in a separate action—especially after denial of consolidation—will not be treated as constructive compliance or a cure for prejudice in the original case.
  • Elevates Rule 26 completeness: The decision highlights that an expert report without timely disclosure of the underlying “facts or data” is not a minor defect; it is a serious Rule 26 violation that supports Rule 37(c)(1) exclusion.
  • Practical litigation consequence: Where an excluded expert is the only damages evidence, Rule 37 exclusion can function as a case-ending sanction, making early compliance and backup evidentiary planning essential.

Although designated “NOT PRECEDENTIAL,” the opinion provides a clear, practice-oriented roadmap that district courts within the Third Circuit may find persuasive, especially in long-running cases with missed expert deadlines.

Complex Concepts Simplified

  • Scheduling order (Rule 16): A court’s case calendar. It remains binding until the judge changes it. Parties cannot assume deadlines “lapse” because the case slows down.
  • Good cause (Rule 16(b)(4)): A legitimate, timely-raised reason why a deadline cannot be met despite diligence—typically shown through a motion to extend filed before (or promptly after) the deadline.
  • Expert disclosures (Rule 26(a)(2)): The expert’s written report must include opinions, reasons, and the “facts or data” the expert considered— automatically, without waiting for an opposing request.
  • Automatic exclusion (Rule 37(c)(1)): If you fail to disclose as required, you generally cannot use that expert/material in motions or at trial unless the failure was “substantially justified” (good reason) or “harmless” (no real prejudice).
  • Daubert motion: A challenge to whether expert testimony is reliable and admissible. Late expert disclosures can force late Daubert litigation, which courts view as disruptive and prejudicial.

Conclusion

Lakeview Pharmacy of Racine, Inc. v. Catamaran Corporation affirms a stringent but familiar enforcement message: expert deadlines and expert-report completeness obligations are not optional, and they are not informally extended by discovery delays or by activity in separate litigation. Where a party neither seeks extensions nor provides timely Rule 26 “facts or data,” and where admitting the expert would impose late-stage burdens and reset case management, exclusion under Rule 37(c)(1) falls comfortably within the district court’s discretion. The case’s practical lesson is stark: if damages require expert proof, missing expert deadlines can be dispositive.