chevron-down Created with Sketch Beta.


Preparing for the Inevitable Battle: Discovery and the Admissibility of Other Similar Incidents

Samuel Lanier Felker and Greggory Jacobs


  • Federal Rule of Civil Procedure 26(b) allows discovery of relevant and proportional information. Relevance is broadly construed, encompassing any matter that could lead to admissible evidence.
  • Four evidentiary functions of prior incidents include proof of defective condition, causation, knowledge of the condition, and negligence in permitting the condition.
  • Prior incidents' evidence must satisfy elements: not offered to prove negligence, similar circumstances, tendency to establish a dangerous condition, and not too remote in time. Failure to establish similarity renders evidence irrelevant.
  • Evidence of conditions before and after an incident may indicate the existence of the same condition at the time of the incident.
Preparing for the Inevitable Battle: Discovery and the Admissibility of Other Similar Incidents
PeopleImages via Getty Images

No matter which side you represent in a products case, you will inevitably clash over the discovery and admissibility of other incidents involving the same or similar products. The plaintiff will seek broad discovery of all prior or subsequent incidents or complaints involving the product at issue or similar products from the beginning of time to the present. The defendant will immediately push back, erecting barriers to obvious “fishing expeditions” about incidents or product models that are not related to the exact product and model at issue and the precise mode of failure or defect that occurred. This familiar battle begins during discovery and then plays out again at trial, depending on what has been uncovered and allowed during discovery. How can the plaintiff strategize to get all that the plaintiff is entitled to during discovery? What arguments and tactics can the defendant use to thwart discovery of potentially damaging evidence that has potential to sway the jury about the company’s safety record and product performance? How does the analysis shift when trial approaches? These subjects are addressed below.

Basic Discovery Rules as a Starting Point

Federal Rule of Civil Procedure 26(b) permits parties to “obtain discovery regarding any nonprivileged matter that is relevant to any party’s claim or defense and proportional to the needs of the case[.]” Fed. R. Civ. P. 26(b)(1). Rule 26 requires the court to consider “the importance of the issues at stake in the action, the amount in controversy, the parties’ relative access to relevant information, the parties’ resources, the importance of the discovery in resolving the issues, and whether the burden or expense of the proposed discovery outweighs its likely benefit.” Id. The opposing party must show “either that the requested discovery (1) does not come within the broad scope of relevance as defined under Rule 26 or (2) is of such marginal relevance that the potential harm occasioned by discovery would far outweigh the ordinary presumption in favor of broad disclosure.” Milinazzo v. State Farm Ins. Co., 247 F.R.D. 691, 695 (S.D. Fla. 2007); see also Gober v. City of Leesburg, 197 F.R.D. 519, 521 (M.D. Fla. 2000) (“The party resisting production bears the burden of establishing lack of relevance or undue burden in supplying the requested information.”).

“Relevance in the context of discovery ‘has been construed broadly to encompass any matter that bears on, or that reasonably could lead to other matter that could bear on, any issue that is or may be in the case.’” Akridge v. Alfa Mut. Ins. Co., 1 F.4th 1271, 1276 (11th Cir. 2021) (quoting Oppenheimer Fund, Inc. v. Sanders, 437 U.S. 340, 351 (1978)). The question of whether material is “‘relevant’ for discovery purposes is ultimately a fact-specific inquiry . . . [and the court has] a broad range of discretion to determine relevance.” Dees v Hyundai Motor Mfg. Ala., LLC, 524 F. Supp. 2d 1348, 1350 (M.D. Ala. 2007) (internal citations omitted). “[S]ince the Rules strongly favor full discovery whenever possible, a civil litigant is generally entitled to any information sought if it appears reasonably calculated to lead to the discovery of admissible evidence.” Akridge, 1 F.4th at 1276 (internal quotation marks and citations omitted). But “[i]nformation within [the] scope of discovery need not be admissible in evidence to be discoverable.” Fed. R. Civ. P. 26(b)(1). In federal court, discovery must also be proportional to the needs of the case, given the issues at stake, the amount in controversy, the parties’ relative access to relevant information, the parties’ resources, the importance of this discovery, and whether the burden or expense of the proposed discovery outweighs its likely benefit. Fed. R. Civ. P. 26(b)(1).

The Doctrine of Substantial Similarity

Despite the breadth of discovery that is allowed in many jurisdictions, discovery requests “must appear reasonably calculated to lead to the discovery of admissible evidence.” Buckhanon v. Opelika Hous. Auth., No. 3:19-cv-893, 2020 WL 10319617, at *2 (M.D. Ala. June 26, 2020). And evidence of prior incidents will be admissible only if “the conditions of the prior incidents are substantially similar to the occurrence in question and are not too remote in time.” Wyatt v. Otis Elevator Co., 921 F.2d 1224, 1227 (11th Cir. 1991). Thus, during discovery, courts will apply the “substantial similarity” doctrine when setting the scope of permissible discovery regarding prior similar incidents. See Foster v. Logan’s Roadhouse, Inc., 2013 WL 1498958, at *3–4 (N.D. Ala. Apr. 4, 2013); Johnson v. U-Haul Int’l, Inc., 2012 WL 13012407, at *2–3 (M.D. Ala. Nov. 15, 2012).

When applying the other similar incidents doctrine, there are four reasons courts permit discovery of other similar incidents. In Gilbert v. Pessin Grocery Co., 132 Cal. App. 2d 212, 282 P.2d 148 (1955), the California Court of Appeal, commenting on Wigmore’s analysis, said:

It will be observed that such proof may serve at least four different evidentiary functions,—as proof of (a) existence of defective or dangerous condition, (b) the cause of the subject accident, (c) knowledge or notice of the dangerous condition, (d) negligence in permitting that condition to continue. But it is not necessary that the proffered evidence of previous accidents be probative in all those respects. If it fairly raises an inference upon one phase of the case it is admissible.

Gilbert, 132 Cal. App. 2d 217; § 106 Rule and Purpose of Admission, 1 Witkin, California Evidence 5th, Circumstantial Evidence § 106 (2022); see also Hasson v. Ford Motor Co., 32 Cal. 3d 388, 403–4, 185 Cal. Rptr. 654, 650 P.2d 1171 (Cal. 1982) (holding that the trial court had reasonable basis for admitting evidence of numerous failures occurring in 1965 models for the purpose of showing that 1966 models were similarly defective even if plaintiffs did not prove that the 1965 system was exactly the same as the 1966 system).

The lesson here: Unless a discovery request is properly calibrated to take into account the factors included in the substantial similarity doctrine, a discovery request directed toward prior similar incidents will not be “reasonably calculated” to lead to the discovery of evidence that is actually admissible.

The case of Alvarez v. Cooper Tire & Rubber Co., 75 So. 3d 789 (Fla. 4th Dist. Ct. App. 2011), demonstrates the application of the other similar incidents doctrine in the discovery setting. In Alvarez, the plaintiff’s personal representative claimed that a defective design of a Cooper-made tire on a truck caused the driver of the truck to lose control, the truck to roll over, and his brother, a passenger in the truck, to be killed. Id. at 790. The plaintiff served discovery requests demanding information and documents regarding all light truck tires manufactured by Cooper. Id. at 791. Cooper objected to the discovery on the basis that it involved trade secret material, that it was burdensome, and that the plaintiff was entitled to discovery only for those tires which were substantially similar to the tire that was the subject of the lawsuit (which was produced pursuant to Green Tire Specification 3011 and was substantially similar to Green Tire Specification 3163). The plaintiff claimed that all tires manufactured to Green Tire Specifications (GTSs) were substantially similar in that all Cooper tires were manufactured using the same basic processes. In response, Cooper argued that there were differences in the processing and specifications that made each GTS tire different. The trial court limited discovery to the “subject tire and substantially similar tires,” defined as “tires designed and manufactured according to Green Tire Specifications 3011 and 3163.” Id. at 793. The defendant won that battle and limited discovery to the tire at issue and models made with the same, exact specifications.

Similarly, in Caterpillar Industrial, Inc. v. Keskes, 639 So. 2d 1129 (Fla. 5th Dist. Ct. App. 1994), the Florida Fifth District Court of Appeal quashed a discovery order requiring Caterpillar to produce all accident reports from 1978 involving all forklifts that “don’t have cabs.” Such production would have required the disclosure of incident reports of 73 different models and excluded only 16 clearly different models that were “great big ones that have cabs on them.” Id. at 1130. The court made it clear that there must be a connection between the discovery sought and the injury claimed—otherwise, it is an improper fishing expedition. Id.

The bottom line is that the plaintiff must establish substantial similarity before similar accidents or incidents are discoverable. Id. In American Medical Systems, Inc. v. Osborne, 651 So. 2d 209 (Fla. 2d Dist. Ct. App. 1995), a product liability action, the manufacturer sought to quash a discovery order requiring the manufacturer to respond to interrogatories relating to an entire model series of penile implants. The court held that the discovery order was overbroad in light of sworn affidavits from the manufacturer indicating that the particular model involved in the case was different in design and performance from other models within the series. Id. at 210. However, the court also noted that if the plaintiffs were to provide the trial court with proof that there was no significant difference in the different models, this would contradict the manufacturer’s affidavits and the trial court could then revisit the issue. Id. But where a plaintiff intends to adduce evidence of the functioning of related products to prove that the product in question was defective, identical conditions need not be present between the two systems. Substantial similarity is sufficient. See Hasson v. Ford Motor Co., 32 Cal. 3d 388, 403–4, 185 Cal. Rptr. 654, 650 P.2d 1171 (Cal. 1982), disapproved on other grounds in Soule v. General Motors Corp., 8 Cal. 4th 548, 574, 34 Cal. Rptr. 2d 607, 882 P.2d 298 (Cal. 1994).

Stricter Standard for Admissibility

The Florida Supreme Court has explained that “[e]vidence of the occurrence or nonoccurrence of prior accidents is admissible only if it pertains to the use of the same type of appliance or equipment under substantially similar conditions.” Ry. Express Agency, Inc. v. Fulmer, 227 So. 2d 870, 873 (Fla. 1969). A party seeking to admit other similar incidents evidence bears the burden of satisfying four elements: (1) the evidence may not be offered to prove negligence or culpability but may be admissible to show the dangerous character of an instrumentality and to show the defendant’s knowledge; (2) similar accidents must pertain to the same type of appliance or equipment under substantially similar circumstances; (3) evidence must have a tendency to establish a dangerous condition at a specific place; and (4) a prior accident must not be too remote in time to the accident at issue, thereby causing it to lack sufficient probative value. Ford Motor Co. v. Hall-Edwards, 971 So. 2d 854, 858 (Fla. 3d Dist. Ct. App. 2007). As always, at trial the court will consider the potential prejudice to the defendant and jury confusion if evidence of prior incidents is admitted.

The party seeking admission must also lay a sufficient predicate to establish similarity between the two incidents, and a failure to do so renders the evidence irrelevant as a matter of law. Id. at 859. Evidence of problem occurrences involving other products with no showing that the other incidents were caused by substantially similar defects should not be admitted into evidence. For example, in Godfrey v. Precision Airmotive Corp., 46 So. 3d 1020, 1021 (Fla. 5th Dist. Ct. App. 2010), the plaintiffs brought suit for damages they suffered when their airplane crashed, allegedly as a result of a faulty carburetor with a buildup of carbon in the engine. The trial court permitted the plaintiffs to introduce evidence of more than 100 problem occurrences involving other aircraft engines to purportedly show that the defendant was on notice of the carburetor defect. However, the Florida Court of Appeal held that evidence of other engine failures did not meet the similarity requirement for admission of prior accident evidence. In fact, most of the incidents involved larger aircraft built by a competing manufacturer and used a different carburetor than the one used in the engine at issue in the case. Id. at 1022. Moreover, the court held that even if all the other incidents had involved the same engine, that showing alone would not have been sufficient to admit the evidence because there are many other potential causes of carbon buildup, and there was no way of knowing whether the buildup in the other cases was caused by the same condition alleged as a defect in this case. Id.

The requirement of similarity may vary in strictness according to the purpose for which the evidence is introduced. Thus, if offered to show a dangerous condition of a particular thing, the other accident must be connected in some way with that thing; but if offered only to show knowledge or notice of a dangerous condition, an accident at the place—a broader area—may be shown. Sambrano v. City of San Diego, 94 Cal. App. 4th 225, 237 (2001) (quoting 1 Witkin, Evidence, Circumstantial Evidence § 104, at 452 (4th ed. 2000)). When evidence is offered to show only that defendant had notice of a dangerous condition, the requirement of similarity of circumstances is relaxed: “[A]ll that is required . . . is that the previous injury should be such as to attract the defendant’s attention to the dangerous situation.” Hasson, 32 Cal. 3d at 404; see also Buell-Wilson v. Ford Motor Co., 141 Cal. App. 4th 525, 542–43, 46 Cal. Rptr. 3d 147, 162 (2006), as modified on denial of reh’g (Aug. 17, 2006), cert. granted, judgment vacated, 550 U.S. 931 (2007), disapproved of by Kim v. Toyota Motor Corp., 6 Cal. 5th 21, 237 Cal. Rptr. 3d 205, 424 P.3d 290 (Cal. 2018).

When Subsequent Incidents May Be Fair Game

Subsequent incidents may also be discoverable and admissible on the same theories. “Evidence of the existence of a particular condition, relationship, or status . . . before and after an act in question is admissible to indicate the existence of the same status, condition or relationship at the time of the act.” Blank v. Coffin, 20 Cal. 2d 457, 463, 126 P.2d 868 (Cal. 1942); see Slovick v. James I. Barnes Const. Co., 142 Cal. App. 2d 618, 625, 298 P.2d 923 (1956); Roddiscraft v. Skelton Logging Co., 212 Cal. App. 2d 784, 801, 28 Cal. Rptr. 277 (1963) (“An inference that a state of affairs existed at a certain time may be reinforced by evidence that it continued to exist at a subsequent time, provided that too long a period has not elapsed and conditions have not changed.”). It should be noted that subsequent incidents are admissible depending on how they will be used. This point is demonstrated in Ginnis v. Mapes Hotel Corp., 86 Nev. 408 (Nev. 1970). The court stated that while evidence of subsequent accidents ordinarily is not pertinent to the issue of notice or knowledge, such evidence may be considered pertinent in determining whether or not the product was hazardous. Id. at 415. To bring this point home, the court cited Witkin’s California Evidence for the following proposition:

The relevancy of other accidents, whether prior or subsequent, depends on the purpose for which the evidence is offered. A subsequent accident would not be relevant on the issue of knowledge or notice of a possibly dangerous condition at the time of the injury giving rise to the action. But a subsequent accident at the same or a similar place, under the same or similar conditions, is just as relevant as a prior accident to show that the condition was in fact dangerous or defective, or that the injury was caused by the condition.

B. Witkin, California Evidence § 353 (2d ed. 1966)

Ginnis reinforces that proof of defect or causation is the primary basis for discovery and admissibility of subsequent incidents.


No matter which side you represent, with these tools, you can use the “substantially similar” doctrine to your advantage in discovery and at trial. The key is focusing the court on the mode of the subject product failure and the characteristics of the other products and incidents that will or will not make the evidence relevant and admissible at trial.

Note: This article is based in part on a CLE presentation at the 2023 Environmental & Energy, Mass Torts, and Products Liability Litigation Committees’ Joint Regional CLE Program in Vail, Colorado. The panelists were Sam Felker of Baker Donelson, Kristine Meredith of Danko Meredith, and Bryan Coleman of Maynard Cooper.