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Cite as 302 Neb. 88

Trevor Pitts and Rebekah Pitts, a married couple, 

appellants, and Haco Electric Company, 

Incorporated, a Nebraska corporation, 

appellee, v. Genie Industries, Inc., a

Washington corporation, appellee.

___ N.W.2d ___

Filed January 18, 2019. No. S-18-219.

1. Summary Judgment: Appeal and Error. An appellate court reviews 

the district court’s grant of summary judgment de novo, viewing the 

record in the light most favorable to the nonmoving party and drawing 

all reasonable inferences in that party’s favor.

2. Trial: Expert Witnesses: Appeal and Error. An appellate court reviews 

de novo whether the trial court applied the correct legal standards for 

admitting an expert’s testimony. But a trial court’s ruling in receiving 

or excluding an expert’s testimony which is otherwise relevant will be 

reversed only when there has been an abuse of discretion.

3. Judges: Words and Phrases. A judicial abuse of discretion exists when 

a judge, within the effective limits of authorized judicial power, elects 

to act or refrain from acting, but the selected option results in a decision which is untenable and unfairly deprives a litigant of a substantial 

right or a just result in matters submitted for disposition through a judicial system.

4. Summary Judgment: Appeal and Error. An appellate court will 

affirm a lower court’s grant of summary judgment if the pleadings and 

admitted evidence show that there is no genuine issue as to any material 

facts or as to the ultimate inferences that may be drawn from those facts 

and that the moving party is entitled to judgment as a matter of law. In 

the summary judgment context, a fact is material only if it would affect 

the outcome of the case.

5. Products Liability: Actions: Negligence. In a products liability cause 

of action based on strict liability in tort, the central question involves 

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the quality of the manufactured product, that is, whether the product was 

unreasonably dangerous.

6. Products Liability: Words and Phrases. “Unreasonably dangerous” 

means that the product has a propensity for causing physical harm 

beyond that which could be contemplated by the ordinary user or 

consumer.

7. Products Liability: Proof. In a products liability action based on defect, 

a plaintiff must prove by a preponderance of the evidence that (1) the 

defendant placed the product on the market for use and knew, or in the 

exercise of reasonable care should have known, that the product would 

be used without inspection for defects; (2) the product was in a defective condition when it was placed on the market and left the defendant’s 

possession; (3) the defect is the proximate or a proximately contributing 

cause of the plaintiff’s injury sustained while the product was being 

used in a way and for the general purpose for which it was designed and 

intended; (4) the defect, if existent, rendered the product unreasonably 

dangerous and unsafe for its intended use; and (5) the plaintiff’s damages were a direct and proximate result of the alleged defect.

8. Products Liability: Negligence: Proximate Cause: Proof. To establish 

proximate cause in a products liability action, the plaintiff must meet 

three basic requirements: (1) Without the defect, the injury would not 

have occurred, commonly known as the “but for” rule or “cause in fact”; 

(2) the injury was a natural and probable result of the defect; and (3) 

there was no efficient intervening cause.

9. Expert Witnesses: Testimony. Findings of fact as to technical matters beyond the scope of ordinary experience are not warranted in the 

absence of expert testimony supporting such findings.

10. Trial: Expert Witnesses. With respect to the requirement of expert testimony, the test is whether the particular issue can be determined from 

the evidence presented and the common knowledge and usual experience of the fact finders.

11. Summary Judgment. Conclusions based on guess, speculation, conjecture, or a choice of possibilities do not create material issues of fact for 

purposes of summary judgment.

12. Rules of Evidence: Expert Witnesses. When a court is faced with a 

decision regarding the admissibility of expert opinion evidence, the trial 

judge must determine at the outset, pursuant to the evidence rule governing expert witness testimony, whether the expert is proposing to testify 

to (1) scientific, technical, or other specialized knowledge that (2) will 

assist the trier of fact to understand or determine a fact in issue.

13. Courts: Expert Witnesses. In evaluating expert opinion testimony 

under Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 
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113 S. Ct. 2786, 125 L. Ed. 2d 469 (1993), and Schafersman v. Agland 

Coop, 262 Neb. 215, 631 N.W.2d 862 (2001), where such testimony’s 

factual basis, data, principles, methods, or their application are called 

sufficiently into question, the trial judge must determine whether the 

testimony has a reliable basis in the knowledge and experience of the 

relevant discipline.

14. Expert Witnesses: Words and Phrases. Expert testimony based upon 

possibility or speculation is insufficient to establish causation; it must be 

stated as being at least probable, in other words, more likely than not.

15. Negligence: Products Liability. The malfunction theory is based on the 

same principle underlying res ipsa loquitur, which permits a fact finder 

to infer negligence from the circumstances of the incident, without 

resort to direct evidence of the wrongful act.

16. Products Liability: Proof. Under the malfunction theory, also sometimes called the indeterminate defect theory or general defect theory, a 

plaintiff may prove a product defect circumstantially, without proof of 

a specific defect, when (1) the incident causing the harm was of a kind 

that would ordinarily occur only as a result of a product defect and (2) 

the incident was not, in the particular case, solely the result of causes 

other than a product defect existing at the time of sale or distribution.

17. ____: ____. The malfunction theory simply provides that it is not necessary for the plaintiff to establish a specific defect so long as there is 

evidence of some unspecified dangerous condition or malfunction from 

which a defect can be inferred—the malfunction itself is circumstantial 

evidence of a defective condition.

18. Products Liability: Proximate Cause: Damages: Proof. The malfunction theory does not alter the basic elements of the plaintiff’s burden of 

proof and is not a means to prove proximate cause or damages.

11. Products Liability: Strict Liability: Proof. The malfunction theory is 

applicable in a strict liability manufacturing defect claim.

12. Products Liability: Proof. The malfunction theory is not available 

when specific defects are alleged.

Appeal from the District Court for Lancaster County: Darla

J. Ideus, Judge. Affirmed.

Peter C. Wegman, Mark R. Richardson, and Alyssa P. Martin, 

of Rembolt Ludtke, L.L.P., and John W. Ballew, Jr., of Ballew 

Hazen, P.C., L.L.O., for appellants.

Michael L. Moran, of Engles, Ketcham, Olson & Keith, 

P.C., for appellee Haco Electric Company, Incorporated.
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Michael F. Coyle and Timothy J. Thalken, of Fraser Stryker, 

P.C., L.L.O., for appellee Genie Industries, Inc.

Heavican, C.J., Miller-Lerman, Cassel, Stacy, Funke, 

Papik, and Freudenberg, JJ.

Freudenberg, J.

NATURE OF CASE

An electrician was injured when an aerial lift malfunctioned and tipped over while the electrician was working 

approximately 30 feet in the air on the lift’s raised platform. 

After sustaining serious injuries, the electrician brought strict 

liability claims, negligence claims, and an implied warranty 

claim against Genie Industries, Inc. (Genie), the manufacturer and designer of the lift. Genie moved for summary 

judgment as to all of the electrician’s claims and sought 

to exclude the electrician’s expert opinions on the issues 

of unreasonably dangerous conditions, defect, causation, and 

alternative design. Following a hearing, the district court partially granted Genie’s motion to exclude expert testimony and 

granted Genie’s motion for summary judgment on all claims. 

The electrician appeals.

FACTS

Aerial Lift

Genie manufactured an aerial lift named Genie model 

“TZ-34/20.” In order to operate the lift, an operator stands 

on a platform, or “bucket” or “basket,” and the platform is 

raised and lowered. The platform is raised and lowered by 

an extension of the lift referred to as a “boom.” The lift sits 

atop of four outriggers that can be retracted when the lift is 

being transported. The outriggers are intended to extend, make 

contact with the ground, and raise the lift off the ground in a 

level manner.

The user operates the lift by pressing buttons on one of 

two control panels: (1) a ground control panel that operates 

the outriggers, boom, and platform and (2) a platform control 
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panel located directly on the platform that operates only the 

boom and the platform. There is also a key switch located at 

the platform controls that selects which of these two controls 

will operate. For example, when the key switch is turned to 

the platform setting, the ground controls will not operate. In 

theory, an operator standing on the platform should not be able 

to move or control the outriggers by pressing buttons on the 

platform control panel. This mechanism was designed to avoid 

destabilization while an operator is on the platform.

The lift in question was sold by Genie to Nebraska Machinery 

Company (Nebraska Machinery) in May 2011. Over the next 

few years, a number of repairs were performed on the lift. 

According to Nebraska Machinery’s work orders, the lift was 

first repaired in August 2011, 4 months after the sale, when the 

“limit switch” failed, which caused the lift to become incapable 

of lowering. In the 2 years prior to the electrician’s accident, 

there were approximately 30 total work orders for repairs on 

this particular lift, several of which related to issues with the 

“auto-leveling” system and the outriggers.

Genie started manufacturing this type of lift in 2003 and has 

made more than 4,600 of them. Genie is not aware of any other 

lift falling over in the same manner on any other occasion. 

During the end of the manufacturing process, Genie tested the 

lift’s functions and determined that the tested movement functions worked properly. Genie’s senior product safety manager 

testified that the lift’s design was consistent with all relevant 

national standards and that in his opinion, the lift’s design 

used the best technology reasonably available at the time it 

was made.

Accident

In June 2013, Nebraska Machinery leased the lift to a general contractor for use at a jobsite in Seward, Nebraska. Trevor 

Pitts is an electrician and was working for an electrical subcontractor. On August 21, the lift tipped over while Pitts was 

working on the platform approximately 30 feet in the air. Pitts 

had used the lift without any problems for 10 days before the 
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accident. On the day of the accident, other subcontractors had 

used the lift less than an hour before the incident.

There appeared to be electrical tape over a button on the 

platform control panel, but Pitts did not know why the tape 

was on the button or who put it there. According to Genie, 

the button that was taped over was the button that levels the 

platform when it is in the air. Genie argues that this indicates 

that the leveling system was altered after the machine left 

Genie’s possession.

After the accident, bystanders who came to the scene saw 

that the left rear outrigger was “retracted.” As a result of that 

outrigger’s being shorter than the others, the lift was not level 

and tipped over, causing Pitts’ injuries.

Pitts and his wife brought several claims against Genie (and 

two other parties, now dismissed) in the Lancaster County 

District Court. These claims included three strict liability 

claims for manufacturing and design defects and a failure to 

warn, three negligence claims, one breach of implied warranty 

claim, and a loss of consortium claim.

Dr. John Boye’s Testimony

The Pittses’ sole expert was an electrical engineer, Dr. 

John Boye. Boye is a professor emeritus in the University of 

Nebraska-Lincoln electrical and computer engineering department who holds a Ph.D. in electrical engineering. Along with 

another electrical engineer, Boye also formed a small electrical 

engineering consulting firm as a licensed electrical and computer engineer with the state. Boye had never before examined, 

used, repaired, or designed an aerial lift. He also had never 

reviewed any other lift in the industry.

In preparing his expert report, Boye reviewed video footage 

from a November 2014 inspection that he did not attend. In 

the video, at least 20 different malfunctions of the left outrigger occurred. He also reviewed several photographs taken at 

the time of the accident and from the 2014 inspection, some 

technical documents, the work order history, depositions, and 

a fuel log from Nebraska Machinery. The extensive work order 
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history and fuel log indicated that the auto-leveling system 

was not working correctly prior to the date of the accident.

Boye reported that the photographs from the 2014 inspection showed the wiring inside the ground control panel was 

“not well done.” He explained that the leads of the diodes were 

not insulated and were very close together. Boye describes 

a diode as an electrical device that allows current to flow in 

one direction.

Boye later participated in a physical inspection of the lift 

in November 2015. In the year since the November 2014 

inspection, the lift remained in the sole possession of Nebraska 

Machinery. However, when Boye completed his 2015 inspection, the lift behaved differently than it did in 2014. In his 

report, Boye explained that the lift clearly malfunctioned in the 

2014 videos but that during the 2015 inspection, the lift either 

did not malfunction at all or malfunctioned differently when 

posed with the same tests. Based on the machine’s failing to 

malfunction as it did in 2014 and at the time of the accident, 

Boye assumed that the lift had been altered between 2014 and 

2015. Because of the lift’s alleged alteration, Boye opined 

that the “[parties] may never be able to find [out] what was 

wrong originally.”

Boye reported generally that the accident occurred from an 

electrical malfunction. However, based on his overall observations, Boye was unable to precisely pinpoint what component 

caused the lift to malfunction on the day of Pitts’ accident. 

Although his report proposed an “overview of a few possibilities” that could have been the cause of the malfunction, 

he conceded several times that he had no opinion as to what 

specifically failed on August 21, 2013.

The possible causes of the electrical malfunction were (1) 

incorrect or shorted wiring; (2) bad components, such as bad or 

touching diodes; (3) other bad or faulty components; (4) failed 

or stuck limit switches; (5) the sticking of failed or “worn out” 

switches, buttons, and relays; and (6) potential movement earlier in the day of the accident which loosened diodes or wires 
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and could have caused a short-circuit. He also thought the 

taped button on the platform control panel may have been a 

factor, but he was unsure how.

Boye reported that Genie’s technical schematics and diagrams had at least 19 “errors and inconsistencies.” In other 

words, in reviewing seven pages of the “Genie Service Manual” 

and six sheets of the “ED, TZ34 DC Control” drawings, Boye 

identified multiple inconsistencies between these documents as 

to the lift’s design. However, he did not opine that the documents identified design defects. Boye stated that he was never 

provided a number of documents that would have helped in the 

evaluation, including certain design documents and other specifications and technical information regarding circuit elements. 

He admitted in his deposition that these missing documents are 

critical to understanding the design.

Boye opined that the lift “could have been designed better.” In particular, he suggested that Genie could have used 

a “4-position keyed switch” instead of a “3-position keyed 

switch.” As designed, the lift has a three-position switch in 

which the user turns a key to activate either the platform control panel or the ground control panel or turns off the machine. 

It is designed so that only one control panel can be activated 

at a given time, and none of the buttons on the platform controls should operate the outriggers. Still, Boye explained that 

this technology could fail if diodes fail. In other words, power 

could be sent to the outriggers even if the switch was in “platform” position, if diodes failed.

Considering the current design, Boye proposed a fourposition switch as an alternative design which would have 

“totally isolate[ed] the outrigger power from the platform 

control panel.” He testified as to his design in a deposition 

and stated that the three-position switch increased the risk of 

a particular kind of electrical diode failure. But Boye admitted 

that this four-position switch design could also fail. He also 

admitted that this proposed four-position switch design would 

require a completely revamped circuitry “from scratch.” Boye’s 
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opinion was not peer reviewed, nor did Boye test or analyze 

the feasibility of a four-position switch design.

In 2017, Boye wrote and signed an additional affidavit for 

the purposes of clarifying his testimony. This affidavit stated 

that the lift tipped over because of an “electrical malfunction 

in the lift’s circuit[r]y.” In the same affidavit, he again opined 

that he could not determine the exact cause of the accident, 

but that the lift was in an unreasonably dangerous condition 

when it left Genie’s possession, because the platform and 

ground control circuitry were interconnected, the diodes and 

wires were too close together, the diodes and wires did not 

have protective sheathing, and a three-position switch design 

was used as opposed to a proposed four-position switch. 

Boye did not elaborate as to the foundation of his conclusion that these defects were present at the time it left Genie’s 

possession and did not retract his prior testimony that six or 

more possible causes could have resulted in the lift’s electrical malfunction.

Motions to Exclude Expert Testimony

and Summary Judgment

Genie moved to exclude Boye’s testimony and for summary judgment. The district court granted Genie’s motion 

to exclude testimony in part and denied it in part. The court 

held that Boye’s opinions regarding alternative design were 

not admissible as they were not relevant and lacked reliability 

under a Daubert/Schafersman1 analysis. However, the district 

court overruled Genie’s motion to exclude testimony regarding Boye’s opinions that the lift was unreasonably dangerous because the platform control and ground control circuitry 

were “‘interconnected,’” the diodes and wires were too close 

together, and the diodes and wires lacked adequate sheathing.

1 See Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. 

Ct. 2786, 125 L. Ed. 2d 469 (1993), and Schafersman v. Agland Coop, 262 

Neb. 215, 631 N.W.2d 862 (2001).
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The court then granted Genie’s motion for summary judgment. The court held that the Pittses lacked the necessary 

expert testimony for the proximate cause element of their 

negligence and product liability claims. Boye’s expert testimony, the court explained, only speculated a “‘choice of possibilities’” as to causation, and such testimony did not create 

a fact question on summary judgment. The court held that the 

malfunction theory could not be used to create a material issue 

for proximate cause in this case because Boye pointed to several specific defects. With no expert evidence to show that the 

lift was defective at the time it left Genie’s possession or that 

the defects proximately caused the platform controls to operate 

the outriggers, the district court granted summary judgment in 

favor of Genie on all claims.

ASSIGNMENTS OF ERROR

The Pittses assign, reordered and rephrased, that the district 

court erred in (1) finding that Genie was entitled to summary 

judgment on the Pittses’ strict liability design defect claim, 

(2) excluding portions of Boye’s expert testimony, (3) misconstruing the scope of Boye’s opinion regarding causation, 

(4) failing to consider and/or excluding evidence related to 

issues of causation regarding the strict liability design defect 

claim, (5) finding that Genie was entitled to summary judgment with respect to the Pittses’ strict liability manufacturing 

defect claim, and (6) failing to allow the Pittses to proceed on 

and further apply the “malfunction theory” with regard to their 

strict liability manufacturing defect claim.

STANDARD OF REVIEW

[1] An appellate court reviews the district court’s grant of 

summary judgment de novo, viewing the record in the light 

most favorable to the nonmoving party and drawing all reasonable inferences in that party’s favor.2

2 Waldron v. Roark, 298 Neb. 26, 902 N.W.2d 204 (2017).
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[2,3] We review de novo whether the trial court applied the 

correct legal standards for admitting an expert’s testimony.3

But a trial court’s ruling in receiving or excluding an expert’s 

testimony which is otherwise relevant will be reversed only 

when there has been an abuse of discretion.4 A judicial abuse 

of discretion exists when a judge, within the effective limits of 

authorized judicial power, elects to act or refrain from acting, 

but the selected option results in a decision which is untenable and unfairly deprives a litigant of a substantial right or a 

just result in matters submitted for disposition through a judicial system.5

ANALYSIS

The Pittses contend that the district court erred in granting Genie’s motion for summary judgment against their strict 

products liability design and manufacturing defects claims. The 

Pittses argue that they presented sufficient evidence that the lift 

was defectively designed, unreasonably dangerous, and defectively manufactured at the time the lift left Genie’s possession to create a genuine dispute rendering summary judgment 

improper. They add that they presented sufficient evidence of 

causation as it relates to Pitts’ injuries.

[4] In reviewing a summary judgment, an appellate court 

views the evidence in the light most favorable to the party 

against whom the judgment was granted, and gives that party 

the benefit of all reasonable inferences deducible from the 

evidence.6 An appellate court will affirm a lower court’s grant 

of summary judgment if the pleadings and admitted evidence 

show that there is no genuine issue as to any material facts or 

as to the ultimate inferences that may be drawn from those 

3 King v. Burlington Northern Santa Fe Ry. Co., 277 Neb. 203, 762 N.W.2d 

24 (2009).

4 Schafersman v. Agland Coop, supra note 1.

5 Id.

6 Green v. Box Butte General Hosp., 284 Neb. 243, 818 N.W.2d 589 (2012).
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facts and that the moving party is entitled to judgment as a 

matter of law.7 In the summary judgment context, a fact is 

material only if it would affect the outcome of the case.8

[5,6] In a products liability cause of action based on strict 

liability in tort, the central question involves the quality of the 

manufactured product, that is, whether the product was unreasonably dangerous.9

 “Unreasonably dangerous” means that the 

product has a propensity for causing physical harm beyond 

that which could be contemplated by the ordinary user or consumer.10 Whether the product is in a defective condition and 

is unreasonably dangerous to its user are generally questions 

of fact.11

[7] In a products liability action based on defect, a plaintiff 

must prove by a preponderance of the evidence that (1) the 

defendant placed the product on the market for use and knew, 

or in the exercise of reasonable care should have known, that 

the product would be used without inspection for defects; (2) 

the product was in a defective condition when it was placed on 

the market and left the defendant’s possession; (3) the defect 

is the proximate or a proximately contributing cause of the 

plaintiff’s injury sustained while the product was being used in 

a way and for the general purpose for which it was designed 

and intended; (4) the defect, if existent, rendered the product 

unreasonably dangerous and unsafe for its intended use; and 

(5) the plaintiff’s damages were a direct and proximate result 

of the alleged defect.12

7 Freeman v. Hoffman-La Roche, Inc., 300 Neb. 47, 911 N.W.2d 591 (2018).

8 See id.

9 See, Stahlecker v. Ford Motor Co., 266 Neb. 601, 667 N.W.2d 244 (2003); 

Freeman v. Hoffman-La Roche, Inc., 260 Neb. 552, 618 N.W.2d 827 

(2000); Rahmig v. Mosley Machinery Co., 226 Neb. 423, 412 N.W.2d 56 

(1987).

10 Hancock v. Paccar, Inc., 204 Neb. 468, 283 N.W.2d 25 (1979).

11 Rahmig v. Mosley Machinery Co., supra note 9.

12 See Jay v. Moog Automotive, 264 Neb. 875, 652 N.W.2d 872 (2002).
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[8] Proximate cause is the cause that in a natural and continuous sequence unbroken by an efficient intervening cause, 

produces the injury, and without which the injury would not 

have occurred.13 To establish proximate cause in a products liability action, the plaintiff must meet three basic requirements: 

(1) Without the defect, the injury would not have occurred, 

commonly known as the “but for” rule or “cause in fact”; (2) 

the injury was a natural and probable result of the defect; and 

(3) there was no efficient intervening cause.14

[9,10] Findings of fact as to technical matters beyond the 

scope of ordinary experience are not warranted in the absence 

of expert testimony supporting such findings.15 With respect 

to the requirement of expert testimony, the test is whether the 

particular issue can be determined from the evidence presented 

and the common knowledge and usual experience of the fact 

finders.16 This case involves the mechanical functioning of 

an aerial lift, its component parts, and its electrical circuitry, 

which are technical matters well outside the scope of ordinary 

experience. Therefore, to create a material issue of fact, the 

Pittses were required to present expert testimony that a defective product caused the malfunction that led to Pitts’ injuries. 

Their only expert was Boye. Thus, the question is whether 

Boye’s testimony created issues of fact as to each element of 

their products liability claims.17

The notion of a defective product embraces two separate 

concepts—a manufacturing defect and a design defect.18 A 

manufacturing defect is one in which the product differs from 

13 Hughes v. School Dist. of Aurora, 290 Neb. 47, 858 N.W.2d 590 (2015).

14 See, generally, Roskop Dairy v. GEA Farm Tech., 292 Neb. 148, 871 

N.W.2d 776 (2015).

15 Id.

16 McVaney v. Baird, Holm, McEachen, 237 Neb. 451, 466 N.W.2d 499 (1991).

17 See, Freeman v. Hoffman-La Roche, Inc., supra note 7; Roskop Dairy v. 

GEA Farm Tech., supra note 14.

18 See Freeman v. Hoffman-La Roche, Inc., supra note 9.
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the specifications and plan of the manufacturer, while a design 

defect is one in which the product meets the specifications of 

the manufacturer, but nonetheless poses an unreasonable risk 

of danger.19 We first address the Pittses’ assignments of error 

related to a design defect.

Design Defect

The Pittses argue that they presented sufficient evidence to 

show that defectively designed circuitry was the proximate 

cause of the electrical malfunction that ultimately caused 

Pitts’ injuries. They argue that the district court, in concluding that Boye’s testimony was speculative and inadequate to 

create a material issue of fact as to causation, misunderstood 

and mischaracterized Boye’s expert testimony. According to 

the Pittses, Boye testified with sufficient certainty that the 

electrical malfunction was caused by one of several possible 

reasons, all of which could be attributed to design defects that 

created an unreasonable danger of an electrical malfunction. 

We disagree.

[11] An expert must have “good grounds” for his or her 

belief in every step of the analysis.20 The term “good grounds” 

means an inference or assertion derived by scientific method 

and supported by appropriate validation.21 Good grounds do 

not include conclusions based on guess, speculation, conjecture, or a choice of possibilities.22 Conclusions based on 

guess, speculation, conjecture, or a choice of possibilities do 

not create material issues of fact for purposes of summary 

judgment.23

Boye initially presented an “overview of a few possibilities” that could have been the cause of the malfunction, none 

19 See id.

20 Roskop Dairy v. GEA Farm Tech., supra note 14.

21 Id.

22 See id.

23 Marksmeier v. McGregor Corp., 272 Neb. 401, 722 N.W.2d 65 (2006).
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of which he directly identified as specifically relating to the 

product’s design. Indeed, several possible causes appear to be 

things that would have occurred after the lift left Genie’s possession. The possible causes of the electrical malfunction were: 

(1) incorrect or shorted wiring; (2) bad components, such as 

bad or touching diodes; (3) other bad or faulty components; (4) 

failed or stuck limit switches; (5) the sticking of failed or “worn 

out” switches, buttons, and relays; and (6) potential movement 

earlier on the day of the accident which loosened diodes or 

wires and could have caused a short circuit. He also thought 

the taped button on the platform control panel may have been 

a factor, but he was unsure how. He asserted that Genie’s 

three-position switch design could have been the cause of the 

malfunction and provided, albeit untested and not reviewed by 

peers, a four-position switch design as an alternative.

Boye later attempted to clarify his opinion in a supplemental affidavit that was admitted into evidence by the district 

court. In the affidavit, he opined that the lift was unreasonably dangerous when it left Genie’s possession because (1) the 

platform and ground control circuitry were interconnected, (2) 

the diodes and wires were too close together, (3) the diodes 

and wires did not have proper protective sheathing, and (4) 

Genie utilized a three-position switch design as opposed to a 

proposed four-position switch. In the affidavit, Boye did not 

retract his prior testimony that he had no opinion as to what 

specifically failed and caused the accident on August 21, 2013. 

In making its decision, the district court considered only the 

first three elements of Boye’s opinion from the affidavit; it 

excluded the alternate design of a four-position switch.

[12,13] First, we find that the district court did not abuse 

its discretion in determining that Boye was not qualified to 

opine that the specific underlying design defect was the failure 

to design the lift with a four-position switch. When a court 

is faced with a decision regarding the admissibility of expert 

opinion evidence, the trial judge must determine at the outset, pursuant to the evidence rule governing expert witness 
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testimony, whether the expert is proposing to testify to (1) 

scientific, technical, or other specialized knowledge that (2) 

will assist the trier of fact to understand or determine a fact 

in issue.24 This entails a preliminary assessment whether the 

reasoning or methodology underlying the testimony is valid 

and whether that reasoning or methodology properly can be 

applied to the facts in issue.25 In evaluating expert opinion 

testimony under Daubert/Schafersman, where such testimony’s 

factual basis, data, principles, methods, or their application are 

called sufficiently into question, the trial judge must determine 

whether the testimony has a reliable basis in the knowledge 

and experience of the relevant discipline.26

It is undisputed that Boye had expertise in the field of 

electrical engineering, but Boye testified that he did not know 

how any other aerial lifts are designed and admitted he was 

unaware of the standards used in the industry for the design 

and manufacture of machines of this nature. He provided no 

evidence of any other lift manufacturer’s utilizing a fourposition switch design. He stated that his four-position switch 

design was conceptual. He did not actually create and test his 

theory, nor was his assertion peer reviewed by other electrical 

engineers. He further asserted that, even with a four-position 

switch instead of Genie’s three-position switch, an electrical 

malfunction could still have occurred. Without testing, peer 

review, and knowledge of whether this theory or alternative 

design would be generally accepted in the industry, Boye’s 

expert opinion that the lift should have been designed with a 

four-position switch was simply unreliable under a Daubert/

Schafersman analysis. As such, the district court did not abuse 

its discretion in determining that Boye lacked knowledge in 

the relevant discipline to testify that the lift should have been 

24 Schafersman v. Agland Coop, supra note 1. See, also, Neb. Evid. R. 702, 

Neb. Rev. Stat. § 27-702 (Reissue 2016).

25 Schafersman v. Agland Coop, supra note 1.

26 Id.
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designed with a four-position switch and in excluding those 

portions of his testimony.

As to the remainder of Boye’s testimony that was admitted into evidence, we find that the district court did not err in 

granting summary judgment in favor of the Pittses. Boye, as 

a qualified and trained electrical engineer, reviewed pictures, 

diagrams, and charts related to the wiring and schematics of 

the machine. Boye generally opined that the lift was unreasonably dangerous in its design because it had inadequate sheathing, interconnected circuitry, and that diodes that were too 

close in proximity. Essentially, his affidavit testimony asserts 

that these unreasonably dangerous conditions are defects in 

Genie’s design. However, Boye testified that any one of a 

number of problems or occurrences, including those not linked 

to design and outside of Genie’s control after the point of sale, 

could have been the actual cause of the electrical malfunction 

that resulted in Pitts’ injuries.

Specifically, Boye stated that one of six or more possibilities could have been the cause of the accident. While some of 

the initial report’s “possibilities” could possibly be connected 

to the affidavit’s “unreasonably dangerous” elements of the 

design, others cannot. For example, Boye stated that a failed 

limit switch, faulty components or diodes, or even recalled 

parts could have been the cause of the malfunction. He even 

stated that incorrect, damaged, or shorted wiring could have 

easily caused the malfunction, which he notes was altered or 

repaired just months prior to Pitts’ accident. He also stated that 

the taped leveling button could have been a cause of the accident. Boye was unable to precisely pinpoint what component 

caused the lift to malfunction on the day of Pitts’ accident. 

Although his report proposed an “overview of a few possibilities” that could have been the cause of the malfunction, 

he conceded several times that he had no opinion as to what 

specifically failed on August 21, 2013.

Some courts have held that a particular product may be 

sufficiently identified as having caused harm even though 
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the evidence does not exclude every other possible cause.27

However, courts clarify that, though the plaintiff is not required 

to eliminate all possible causes, the plaintiff must still establish 

a logical sequence of cause and effect between the defect and 

the injury.28 We need not decide in this case if the Pittses were 

required to eliminate all possible nondesign causes in order to 

create a material issue of fact, because even if they were not, 

the evidence’s logical sequence of cause and effect was lacking. In other words, Boye did not opine with a requisite degree 

of certainty that any of the “possibilities” was the one that 

caused the malfunction.

[14] We have held that expert testimony “based upon possibility or speculation is insufficient [to establish causation]; 

it must be stated as being at least ‘probable,’ in other words, 

more likely than not.”29 Even assuming that Boye’s reasons 

for the lift’s being in an “unreasonably dangerous condition” 

were all affirmatively connected to the lift’s design, he failed 

to sufficiently connect the possible causes of the malfunction stated in his report to these design defects. Throughout 

his opinion, Boye merely speculated that defects could have 

been related to the ultimate cause of the malfunction, while 

also proposing potential causes that overtly did not relate to 

Genie’s design, such as the failure of a limit switch, the taped 

over leveling button, or faulty components. Because of the 

intermingling of possible causes that are related and unrelated 

to the design, with no testimony that any one of them was 

more probable than another, there is no way for a fact finder 

to determine without speculation whether a defective design 

27 See 49 Am. Jur. Proof of Facts 2d 293 Defect Not Cause § 3 (1987 & 

Supp. 2018).

28 See id. See, also, Whitmire v. Terex Telelect, Inc., 390 F. Supp. 2d 540 

(E.D. Tex. 2005); Skinner v Square D Co, 445 Mich. 153, 516 N.W.2d 

475 (1994); MASB-SEG v. Metalux, 231 Mich. App. 393, 586 N.W.2d 549 

(1998).

29 Fackler v. Genetzky, 263 Neb. 68, 74, 638 N.W.2d 521, 528 (2002). 

Accord Barrett v. Rhodia, Inc., 606 F.3d 975 (8th Cir. 2010).
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was the proximate cause of the electrical malfunction and 

Pitts’ injuries.

In sum, Boye’s testimony as to causation was too speculative for a jury to conclude that the specific alleged design 

defect or defects were the “but for” cause of the electrical 

malfunction leading to Pitts’ injuries. Because failure of proof 

concerning an essential element of the nonmoving party’s case 

on a motion for summary judgment necessarily renders all 

other facts immaterial,30 we hold that the district court did not 

err in finding that there remained no genuine issue of fact as to 

the element of causation and that Genie was entitled to judgment as a matter of law on the Pittses’ strict liability design 

defect claim.

Manufacturing Defect and

Malfunction Theory

In addition to the Pittses’ design defect claim, they assert 

that the district court erred in granting summary judgment 

against their strict liability manufacturing defect claim. The 

Pittses rely on what is known as the malfunction theory to 

support the causation prong of this claim. They contend that 

although they presented evidence of specific design defects, 

they did not present any direct evidence that there was a specific manufacturing defect. They assert that in lieu of proving a specific manufacturing defect, the malfunction theory 

allows them to circumstantially prove an unspecified defect 

in the lift.

[15,16] The malfunction theory is based on the same principle underlying res ipsa loquitur, which permits a fact finder to 

infer negligence from the circumstances of the incident, without resort to direct evidence of the wrongful act.31 Under the 

malfunction theory, also sometimes called the indeterminate 

defect theory or general defect theory,32 a plaintiff may prove 

30 See Freeman v. Hoffman-La Roche, Inc., supra note 7.

31 Roskop Dairy v. GEA Farm Tech., supra note 14.

32 Id.
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a product defect circumstantially, without proof of a specific 

defect, when (1) the incident causing the harm was of a kind 

that would ordinarily occur only as a result of a product defect 

and (2) the incident was not, in the particular case, solely the 

result of causes other than a product defect existing at the time 

of sale or distribution.33

[17,18] The malfunction theory is narrow in scope. The 

theory simply provides that it is not necessary for the plaintiff 

to establish a specific defect so long as there is evidence of 

some unspecified dangerous condition or malfunction from 

which a defect can be inferred—the malfunction itself is circumstantial evidence of a defective condition.34 The malfunction theory does not alter the basic elements of the plaintiff’s 

burden of proof and is not a means to prove proximate cause or 

damages.35 Although some circumstances may justify the use 

of the malfunction theory to bridge the gap caused by missing evidence, the absence of evidence does not make a fact 

more probable but merely lightens the plaintiff’s evidentiary 

burden despite the fact that the missing evidence might well 

have gone either way, and this rationale is too often subject 

to misapplication by courts in situations in which evidence is 

actually available.36

As a matter of policy, the malfunction theory is meant to 

allow circumstantial proof of a product defect without evidence of the specific defect, because in many instances, the 

dealer or manufacturer has either purposefully or inadvertently 

tampered with the evidence.37 When examination of the product unit is impossible because the unit is lost or destroyed 

after the harm-causing incident, responsibility for spoliation 

33 Id. (citing Restatement (Third) of Torts: Products Liability § 3, comment 

a. (1998)).

34 Roskop Dairy v. GEA Farm Tech., supra note 14.

35 Id.

36 Id.

37 Id.
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of evidence may be relevant to the application of the malfunction theory.38

[19] We have yet to expressly hold that the malfunction 

theory applies to strict liability claims,39 but we have made the 

malfunction theory available to plaintiffs in an implied warranty context.40 And we have approved of the general approach 

set forth in the Restatement (Third) of Torts § 2(b)41 that identifies a product defect as the core similarity between strict liability and implied warranty claims, thereby merging theories of 

recovery for implied warranty with theories of recovery based 

on allegations of design or manufacturing defects.42 There is 

no reason to prohibit the malfunction theory in a strict liability 

matter when we do not do so for its implied warranty counterpart. We hold that the malfunction theory is applicable in a 

strict liability manufacturing defect claim.

[20] To support a manufacturing defect through the malfunction theory, the Pittses rely on Boye’s opinion that, given the 

nature of the malfunction that occurred, “the only reasonable 

inference to be drawn from this set of events is that a flaw in 

the lift’s circuitry caused this electrical malfunction.” However, 

they simultaneously point to several specific design defects in 

their design defect claim, as we discussed above. We recently 

held in O’Brien v. Cessna Aircraft Co.43 that the malfunction 

theory is not available when specific defects are alleged.

In O’Brien, a commercial pilot specifically claimed that 

the deicing system on the plane was defectively designed and 

38 See Restatement, supra note 33, comment b.

39 See O’Brien v. Cessna Aircraft Co., 298 Neb. 109, 903 N.W.2d 432 (2017).

40 See, e.g., Genetti v. Caterpillar, Inc., 261 Neb. 98, 621 N.W.2d 529 (2001) 

(holding that precise or specific defect does not need to be proved in order 

to find product defective).

41 Restatement, supra note 33, § 2(b).

42 Freeman v. Hoffman-La Roche, Inc., supra note 9. See, also, Shuck v. CNH 

America, LLC, 498 F.3d 868 (8th Cir. 2007).

43 O’Brien v. Cessna Aircraft Co., supra note 39.
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unreasonably dangerous. He argued that it was defectively 

designed, because the deicing boot provided insufficient coverage and the deicing system lacked a water separator to prevent contaminants from entering and affecting its operation. 

The pilot then attempted to rely on the malfunction theory to 

prove a nonspecific defect that the aircraft was susceptible to 

“‘ice contaminated tail stall.’”44 We held that because the pilot 

alleged that the plane crash was caused by several specific 

design defects, he could not simultaneously rely on the malfunction theory in an effort to prove the accident was caused 

by a nonspecific defect rendering the aircraft susceptible to 

“ice contaminated tail stall.”45

This case mirrors O’Brien in that the Pittses have pointed 

to evidence of specific design defects in the lift that possibly 

caused an electrical malfunction; but, later, in an effort to 

forward his manufacturing defect theory, relied on the malfunction theory by generally asserting that a flaw in the lift’s 

circuitry caused this electrical malfunction. For this reason, the 

malfunction theory is inapplicable in this case and the district 

court did not err in refusing to apply it. We need not address 

whether there are additional reasons why the Pittses failed to 

create a material issue of fact for recovery under the malfunction theory.

There being no other evidence of a manufacturing defect, 

the district court did not err in granting summary judgment 

in favor of Genie on the Pittses’ strict liability manufacturing 

defect claim.

CONCLUSION

For the foregoing reasons, we affirm the district court’s 

grant of summary judgment as to the Pittses’ strict products 

liability defect claim.

Affirmed.

44 Id. at 114, 903 N.W.2d at 443.

45 O’Brien v. Cessna Aircraft Co., supra note 39.