Filed 5/19/15 Sumaya v. Cequent Performance Products CA4/1

NOT TO BE PUBLISHED IN OFFICIAL REPORTS

California Rules of Court, rule 8.1115(a), prohibits courts and parties from citing or relying on opinions not certified for 

publication or ordered published, except as specified by rule 8.1115(b). This opinion has not been certified for publication 

or ordered published for purposes of rule 8.1115. 

COURT OF APPEAL, FOURTH APPELLATE DISTRICT

DIVISION ONE

STATE OF CALIFORNIA

EMILY SUMAYA, a Minor, etc.,

Plaintiff and Appellant,

v.

CEQUENT PERFORMANCE PRODUCTS, 

INC.,

Defendant and Respondent.

D066880

(Super. Ct. No. RIC1106382)

APPEAL from a judgment of the Superior Court of Riverside County, Matthew C. 

Perantoni, Judge. Affirmed.

The Homampour Law Firm, Arash Homampour and Wendi O. Wagner for 

Plaintiff and Appellant. 

Hewitt Wolensky & McNulty, Elizabeth V. McNulty and Jamison E. Power for 

Defendant and Respondent. 

Plaintiff Emily Sumaya (Sumaya), by and through her guardian ad litem, Eh 

Sumaya, appeals from the trial court's summary judgment in favor of defendant Cequent 
2

Performance Products, Inc. (Cequent) in Sumaya's lawsuit alleging strict product liability 

and negligence against Cequent. We conclude that summary judgment was properly 

granted in favor of Cequent because Sumaya is not able to establish the necessary 

element of causation for either of her causes of action. Accordingly, we affirm the 

judgment. 

I

FACTUAL AND PROCEDURAL BACKGROUND

The basic facts that gave rise to this case are undisputed. On the night of 

March 20, 2010, five-year-old Sumaya was a backseat passenger in a Subaru Forester 

driven by her uncle, Ning Yang. As Yang drove in the number three lane of Interstate 10 

in Riverside County, a seven-pound metal draw bar, which is part of a tow hitch 

assembly, crashed through the front windshield of the Subaru, hitting Sumaya in the head 

and severely injuring her. Immediately prior to the incident, Yang saw a large truck in 

front of him in the number four lane, with sparks coming from underneath it, but he saw 

no debris on the freeway and did not notice any disabled or abandoned vehicles or 

trailers. Neither Yang, nor any other witness, saw the draw bar before it struck the 

Subaru or knew how it ended up on the freeway. 

The draw bar that injured Sumaya was manufactured by Cequent and is used to 

connect a tow vehicle to a trailer. As designed, the draw bar is attached to the tow 

vehicle by inserting the draw bar into the tube-shaped receiver hitch installed on the tow 

vehicle. To prevent the draw bar from disengaging from the receiver hitch, a metal pin is 
3

inserted through holes that line up on the receiver hitch and the draw bar, and a clip is 

placed on the pin. 

Sumaya filed a lawsuit against Cequent alleging two causes of action: strict 

product liability and negligence. Sumaya alleges that the draw bar ended up on the 

freeway because of a design defect in the tow hitch assembly or because Cequent failed 

to warn consumers to prevent such an incident. Specifically, Sumaya contends that the 

draw bar was designed so that, when not being used to tow a trailer, it could be inserted 

into the receiver hitch on the tow vehicle without employing the pin and clip. According 

to Sumaya, if the pin and clip are not employed, the draw bar initially remains attached to

the receiver hitch, but the vibrations caused by driving could eventually cause the draw 

bar to come detached from the receiver hitch and end up on the roadway. Sumaya 

contends that Cequent should have warned consumers not to use the draw bar without the 

pin and clip or should have implemented a design feature that would have prevented the 

draw bar from detaching from the tow vehicle when used without a pin and clip and when 

not towing a trailer.1

After conducting discovery, Cequent filed a motion for summary judgment, in 

which it argued that Sumaya could not establish the necessary element of causation for 

 

1 Sumaya's complaint and discovery responses also set forth the theory that the tow 

hitch assembly was defective because it was designed in a way that it could fail while 

towing a trailer, resulting in the draw bar being deposited on the roadway. Sumaya has 

clarified that her current theory of the case is that the tow hitch assembly is defective 

because the draw bar can detach when inserted in a hitch receiver without the use of a pin 

and clip when no trailer is being towed and that Cequent failed to warn of that problem 

or design around it. 
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either of her causes of action because there was no evidence of how the draw bar ended 

up on the freeway and thus no evidence that any product defect caused Sumaya's injuries. 

To meet its initial burden on summary judgment, Cequent submitted, among other things, 

discovery responses from Sumaya in which she admitted that she did not know how the 

draw bar came to be located on the freeway.

In opposition to the motion for summary judgment, Sumaya relied, among other 

things, on the declaration of her expert witness, mechanical engineer James William 

Jones. As Jones opined, the "the only rational explanation" of how the draw bar ended up 

on the freeway was that it vibrated out of a receiver hitch while being driven on the 

freeway, but not being used to tow a trailer, because the pin and clip were either missing 

or improperly inserted. Jones also opined that other theories of how the draw bar came to 

be located on the freeway were not "scientifically probable." Specifically, Jones rejected 

the theory that the draw bar could have (1) "fallen out of the back of a pick-up truck"; 

(2) "fallen out of the back of a moving van"; (3) "fallen out of a dump truck"; (4) "been 

discarded intentionally by a reckless motorist"; or (5) "been a remnant of a prior accident 

lying on the side of the road that got kicked up onto the freeway." (Underscoring 

omitted.) Cequent filed evidentiary objections to portions of Jones's declaration. 

The trial court granted Cequent's motion for summary judgment. 

It also sustained Cequent's evidentiary objections to the portions of Jones's declaration in 

which he opined that (1) the only rational explanation for the draw bar ending up on the 

freeway was that it vibrated out of the receiver hitch because the pin and clip were 
5

missing or improperly inserted; and (2) other theories of how the draw bar came to be 

located on the freeway were not scientifically probable.

Sumaya appeals from the judgment, arguing that the trial court improperly granted 

summary judgment in favor of Cequent and improperly sustained Cequent's objections to 

Jones's declaration. 

II

DISCUSSION

A. The Trial Court Properly Sustained Cequent's Evidentiary Objections

As an initial matter, we consider Sumaya's challenge to the trial court's ruling 

sustaining Cequent's objections to portions of Jones's declaration. 

It is well established that " 'proof of causation cannot be based on . . . an expert's 

opinion based on inferences, speculation and conjecture.' " (Saelzler v. Advanced Group 

400 (2001) 25 Cal.4th 763, 777 (Saelzler).) Based on this principle, Cequent sought to 

exclude Jones's opinion that the draw bar ended up on the freeway because it vibrated out 

of a receiver hitch without the pin and clip being engaged, instead of other possible 

causes, including falling off of a pickup truck, dump truck or moving van, being 

intentionally discarded by a motorist, or ending up on the freeway as the remnant of an 

earlier accident. 

We apply an abuse of discretion standard of review when deciding whether the 

trial court properly sustained Cequent's objections. Although the California Supreme 

Court recently expressly declined to reach the issue in Reid v. Google, Inc. (2010) 50 

Cal.4th 512, 535, the weight of authority, both before and after Reid, holds that an 
6

appellate court applies an abuse of discretion standard when reviewing a trial court's 

rulings on evidentiary objections made in connection with a summary judgment motion. 

(See, e.g., Serri v. Santa Clara University (2014) 226 Cal.App.4th 830, 852; Ahn v. 

Kumho Tire U.S.A., Inc. (2014) 223 Cal.App.4th 133, 143-144; Kincaid v. Kincaid

(2011) 197 Cal.App.4th 75, 82-83; Carnes v. Superior Court (2005) 126 Cal.App.4th 

688, 694.)2 

According to Evidence Code section 801, subdivision (b), expert testimony may 

be excluded if it is not "[b]ased on matter . . . perceived by or personally known to the 

witness or made known to him at or before the hearing, whether or not admissible, that is 

of a type that reasonably may be relied upon by an expert in forming an opinion upon the 

subject to which his testimony relates . . . ." (Ibid.) As our Supreme Court has explained, 

"under Evidence Code section 801, the trial court acts as a gatekeeper to exclude 

speculative or irrelevant expert opinion. . . . '[T]he expert's opinion may not be based "on 

assumptions of fact without evidentiary support [citation], or on speculative or 

conjectural factors. . . . [¶] Exclusion of expert opinions that rest on guess, surmise or 

conjecture [citation] is an inherent corollary to the foundational predicate for admission 

of the expert testimony: will the testimony assist the trier of fact to evaluate the issues it 

 

2 Even were we to apply a de novo standard of review to the trial court's evidentiary 

ruling, we would still conclude that the trial court properly sustained the objections. (See 

Howard Entertainment, Inc. v. Kudrow (2012) 208 Cal.App.4th 1102, 1114 [explaining 

that under any standard of review it would reach the same conclusion regarding the trial 

court's ruling on evidentiary objections made in connection with a summary judgment 

motion].)
7

must decide?" ' " (Sargon Enterprises, Inc. v. University of Southern California (2012)

55 Cal.4th 747, 770 (Sargon).) "[A]n expert's opinion that something could be true if 

certain assumed facts are true, without any foundation for concluding those assumed facts 

exist in the case before the jury, does not provide assistance to the jury . . . ." (Jennings 

v. Palomar Pomerado Health Systems, Inc. (2003) 114 Cal.App.4th 1108, 1117.)

Here, the trial court was well within its discretion to determine that Jones's opinion 

about how the draw bar came to be located on the freeway was based on " ' "assumptions 

of fact without evidentiary support . . . , or on speculative or conjectural factors." ' " 

(Sargon, supra, 55 Cal.4th at p. 770.) 

First, with respect to Jones's conclusion that the draw bar could not have fallen off 

of a pickup truck or a moving van, those conclusions are speculative and based on 

conjecture and are not within any area of expertise claimed by Jones. Jones asserts that 

pickup trucks and moving vans are not normally driven with their tailgates or doors open, 

and that the draw bar could not have fallen out of a closed truck. However, in his 

declaration Jones identified no background that would make him an expert on the way in 

which trucks are driven. Further, Jones cites no reason for concluding that this was not 

one of the instances in which a truck was driven with its doors or tailgate open, in which 

a flatbed pickup truck was used, or one in which the draw bar was inadvertently left on an 

unenclosed area of a truck, such as a bumper or roof. In those instances, the heavy draw 

bar would not have to "bounce out" as Jones describes. 

Jones's opinion that the draw bar could not have fallen out of a dump truck is also 

too speculative and conjectural to be admissible. Jones bases his opinion on the 
8

purported fact that "dump trucks are made in such a way that items do not just 'fall' out 

unless they are very, very light." However, Jones cites no factual basis for this 

assumption or any expertise in the design of dump trucks or the instances in which dump 

trucks might be incorrectly loaded to allow even heavy items to fall off. 

Next, Jones also engages in pure speculation and conjecture when concluding that 

the draw bar could not have been left on the freeway as the remnant of an earlier 

accident. Jones did not review records of previous accidents, and he bases his opinion 

solely on the fact that witnesses observed no other debris on the freeway. However, 

Jones provides no factual basis for the assumption that accident debris, other than the 

draw bar, would still have been on the freeway after an accident that could have occurred 

a substantial amount of time earlier, and he provides no basis for his assumption that the 

witnesses to the accident or the responding officers conducted an adequate search for any 

other debris on the freeway on the night of the accident. 

Jones also cites no sound factual basis for his assumption that the draw bar could 

not have been intentionally thrown onto the freeway. As Jones explained, his conclusion 

is based on the assumption that no one would commit such an act because it would 

presuppose an intent to cause random injury or damage. However, Jones has no basis for 

reaching the conclusion that no one could possibly commit a willfully malicious act, and 

he has no expertise that would allow him to opine on human behavior. Further, Jones 

assumes that someone could not have discarded the drawbar on the freeway because there 

were no eyewitnesses to such an act, but he cites no reason to believe that such an act 
9

would have an eyewitness or that any eyewitness would have been located if such an 

incident had occurred. 

Finally, the trial court properly sustained the objection to Jones's statement that 

"the only rational explanation" for the draw bar being located on the freeway was that it 

vibrated loose and fell onto the freeway because it was inserted in a hitch receiver but the 

pin and clip were missing or were improperly engaged. Although Jones cites no specific 

factual basis for his conclusion, we infer that he reached his conclusion by the process of 

elimination, namely by rejecting the other possible ways that the draw bar could have 

ended up on the freeway. However, as we have explained, Jones provides no sound basis 

for eliminating the other theories of how the draw bar ended up on the freeway, and thus 

he also fails to provide a sound factual basis for reasoning by the process of elimination. 

In sum, we conclude that the trial court properly sustained Cequent's objections to 

Jones's declaration on the basis that Jones's opinions as to how the draw bar ended up on 

the freeway were speculative and based on conjecture.

B. Summary Judgment Was Properly Granted in Favor of Cequent

1. Standard of Review

Code of Civil Procedure section 437c, subdivision (c) provides that summary

judgment is to be granted when there is no triable issue of material fact and the moving 

party is entitled to judgment as a matter of law. A defendant "moving for summary

judgment bears an initial burden of production to make a prima facie showing of the 

nonexistence of any triable issue of material fact." (Aguilar v. Atlantic Richfield Co.

(2001) 25 Cal.4th 826, 850 (Aguilar).) A defendant may meet this burden either by 
10

showing that one or more elements of a cause of action cannot be established or by 

showing that there is a complete defense. (Ibid.) "[T]he defendant may show through 

factually devoid discovery responses that the plaintiff does not possess and cannot 

reasonably obtain needed evidence." (Collin v. CalPortland Company (2014) 228 

Cal.App.4th 582, 587.)

If the defendant's prima facie case is met, the burden shifts to the plaintiff to show 

the existence of a triable issue of material fact with respect to that cause of action or 

defense. (Aguilar, supra, 25 Cal.4th at p. 849; Silva v. Lucky Stores, Inc. (1998) 65 

Cal.App.4th 256, 261.) Ultimately, the moving party "bears the burden of persuasion that 

there is no triable issue of material fact and that he is entitled to judgment as a matter of 

law." (Aguilar, at p. 850.)

We review a summary judgment ruling de novo to determine whether there is a 

triable issue as to any material fact and whether the moving party is entitled to judgment 

as a matter of law. (Certain Underwriters at Lloyd's of London v. Superior Court (2001) 

24 Cal.4th 945, 972.) " 'Since defendant[] obtained summary judgment in [its] favor, "we 

review the record de novo to determine whether [it has] conclusively negated a necessary 

element of the plaintiff's case or demonstrated that under no hypothesis is there a material 

issue of fact that requires the process of trial." ' " (Saelzler, supra, 25 Cal.4th at p. 767.) 

"In practical effect, we assume the role of a trial court and apply the same rules and 

standards which govern a trial court's determination of a motion for summary judgment." 

(Lenane v. Continental Maritime of San Diego, Inc. (1998) 61 Cal.App.4th 1073, 1079.) 

"[W]e are not bound by the trial court's stated reasons for its ruling on the motion; we 
11

review only the trial court's ruling and not its rationale." (Gafcon, Inc. v. Ponsor & 

Associates (2002) 98 Cal.App.4th 1388, 1402.)

2. Legal Standards for Causation

To prevail on either of her causes of action at trial, Sumaya was required to 

establish the element of legal causation. "[U]nder either a negligence or a strict liability 

theory of products liability, to recover from a manufacturer, a plaintiff must prove that a 

defect caused injury." (Merrill v. Navegar, Inc. (2001) 26 Cal.4th 465, 479.) "Liability 

must be predicated upon a showing that a defect in the product was a proximate cause of 

plaintiff's injury." (Thomas v. Lusk (1994) 27 Cal.App.4th 1709, 1716, fn. 3.) 

Case law explains the type of causation that must be established in a product 

liability action and to establish negligence. "A manufacturer is liable only when a defect 

in its product was a legal cause of injury. [Citation.] A tort is a legal cause of injury only 

when it is a substantial factor in producing the injury." (Soule v. General Motors Corp.

(1994) 8 Cal.4th 548, 572.)

Consistent with this principle, in any type of tort action a plaintiff establishes 

causation only if it can show that it is more likely than not that the alleged tortious 

conduct caused the injury. Specifically, to establish causation in fact, " '[t]he plaintiff 

must introduce evidence which affords a reasonable basis for the conclusion that it is 

more likely than not that the conduct of the defendant was a cause in fact of the result. A 

mere possibility of such causation is not enough; and when the matter remains one of 

pure speculation or conjecture, or the probabilities are at best evenly balanced, it becomes 
12

the duty of the court to direct a verdict for the defendant.' " (Ortega v. Kmart Corp.

(2001) 26 Cal.4th 1200, 1205-1206, italics added (Ortega).) 

Because the plaintiff must establish that it is more likely than not that the alleged 

tortious conduct caused the injuries, "[a] plaintiff cannot recover damages based upon 

speculation or even a mere possibility that the wrongful conduct of the defendant caused 

the harm." (Williams v. Wraxall (1995) 33 Cal.App.4th 120, 133, italics added.)

"[E]vidence of causation 'must rise to the level of a reasonable probability based upon 

competent testimony. [Citations.] "A possible cause only becomes 'probable' when, in 

the absence of other reasonable causal explanations, it becomes more likely than not that 

the injury was a result of its action." [Citation.] The defendant's conduct is not the cause 

in fact of harm " 'where the evidence indicates that there is less than a probability, i.e., a 

50-50 possibility or a mere chance,' " that the harm would have ensued.' " (Bowman v. 

Wyatt (2010) 186 Cal.App.4th 286, 312 (Bowman).)

"Where there is evidence that the harm could have occurred even in the absence of 

the defendant's negligence, 'proof of causation cannot be based on mere speculation,

conjecture and inferences drawn from other inferences to reach a conclusion unsupported 

by any real evidence.' " (Padilla v. Rodas (2008) 160 Cal.App.4th 742, 752 (Padilla).)

Although "[t]he plaintiff . . . 'need not prove causation with absolute certainty[,]' "

it must at least " ' " 'introduce evidence which affords a reasonable basis for the 

conclusion that it is more likely than not that the conduct of the defendant was a cause in 

fact of the result.' " ' " (Garbell v. Conejo Hardwoods, Inc. (2011) 193 Cal.App.4th 1563, 

1569.) " '[P]roof that raises mere speculation, suspicion, surmise, guess or conjecture is 
13

not enough to sustain [the plaintiff's] burden' of persuasion." (Izell v. Union Carbide 

Corporation (2014) 231 Cal.App.4th 962, 969.) 

Although there is no question that a plaintiff may establish causation by relying 

solely on circumstantial evidence, a plaintiff attempting to do so must still satisfy the 

standards set forth above. "In deciding whether a plaintiff has met her burden of proof, 

we consider both direct and circumstantial evidence, and all reasonable inferences to be 

drawn from both kinds of evidence, giving full consideration to the negative and 

affirmative inferences to be drawn from all of the evidence, including that which has 

been produced by the defendant. . . . [¶] We will not, however, draw inferences from 

thin air. Where . . . the plaintiff seeks to prove an essential element of her case by 

circumstantial evidence, she cannot recover merely by showing that the inferences she 

draws from those circumstances are consistent with her theory. Instead, she must show 

that the inferences favorable to her are more reasonable or probable than those against 

her." (Leslie G. v. Perry & Associates (1996) 43 Cal.App.4th 472, 483, citations omitted

(Leslie G.).) 

3. Cequent Showed That Sumaya Could Not Establish a Reasonable 

Probability That a Defect in the Tow Hitch Assembly Was a Substantial 

Cause of Her Injuries, as Sumaya's Theory of How the Draw Bar Ended Up 

on the Freeway Was Based Purely on Speculation

Based on the standards for legal causation that we have discussed above, Sumaya 

would have been required at trial to prove a reasonable probability that the draw bar 

ended up on the freeway because of a design defect or failure to warn, and, as a result,

was present on freeway lanes and crashed through Yang's windshield, injuring Sumaya. 
14

(Bowman, supra, 186 Cal.App.4th at p. 312.) To do so, Sumaya would, of course, have 

to establish a reasonable probability that the draw bar was inserted into a receiver hitch 

installed on a vehicle that was driving on the freeway and that it became disengaged from 

the receiver hitch and ended up on the freeway. As we have discussed, Sumaya cannot 

carry her burden of proof by establishing a mere possibility that the draw bar disengaged 

from a receiver hitch on the freeway (Ortega, supra, 26 Cal.4th at p. 1205), and it is not 

sufficient for Sumaya to rely on speculation or conjecture that the draw bar ended up on 

the freeway in that manner. (Padilla, supra, 160 Cal.App.4th at p. 752.) She must 

establish it is more likely than not that the draw bar was located on the freeway because it 

disengaged from a receiver hitch. (Ortega, at p. 1205.) 

Cequent met its initial burden on summary judgment to show Sumaya's inability to 

establish causation by relying on Sumaya's discovery responses. (See Aguilar, supra, 25 

Cal.4th at p. 855 [To meet its initial burden, "[t]he defendant may . . . present evidence 

that the plaintiff does not possess, and cannot reasonably obtain, needed evidence — as

through admissions by the plaintiff following extensive discovery to the effect that he has 

discovered nothing."].) In those discovery responses, Sumaya admitted that she did not 

know how the draw bar ended up on the freeway but stated that she believed it was 

attached to a tow vehicle and disengaged on the freeway. When asked to set forth the 

evidence that supported her belief, Sumaya's discovery responses pointed to documents, 

such as the traffic collision report, photographs of the draw bar, and Sumaya's medical 

records, that contain no information indicating where the draw bar came from. Based on 

these discovery responses, the trial court properly determined that Cequent met its initial 
15

burden to establish that Sumaya could not establish causation. Sumaya's responses to 

discovery show that any finding as to how the draw bar ended up on the freeway would 

be completely speculative and not meet the standard of establishing causation by a 

reasonable probability. 

After the burden shifted to her to establish a triable issue of material fact, Sumaya 

did not identify admissible evidence creating a triable issue regarding causation. Sumaya 

attempted to rely on statements in Jones's declaration opining that the only rational 

explanation for the draw bar's presence on the freeway was that it vibrated out of a 

receiver hitch, but as we have explained, the trial court properly sustained Cequent's 

evidentiary objections to those portions of Jones's declaration. 

In her appellate argument, relying on little more than the fact that the draw bar was 

located on the freeway with no clear indication of how it got there, Sumaya argues that 

the circumstantial evidence supports a finding that it is more likely than not that the draw 

bar ended up on the freeway because it disengaged from a receiver hitch. As Sumaya 

phrases the argument, she believes that, under the circumstances, there is more than an 

"equal probability" that the draw bar disengaged from a receiver hitch. We disagree. 

There are a myriad of possible ways that the draw bar could have ended up on the 

freeway. Using common sense, one very plausible explanation — which is not even 

acknowledged in Jones's declaration — is that the draw bar was inadvertently left on an 

unprotected area of a vehicle, such as a bumper, a roof or the edge of flatbed truck, and 

the driver inadvertently drove onto the freeway where the draw bar eventually fell off. 

Other possibilities, as Jones discusses and fails to persuasively discount, are that the draw 
16

bar could have been intentionally thrown onto the freeway, could have been poorly 

packed into a truck that was transporting it, or could have ended up on the freeway 

shoulder during a serious accident and was eventually kicked up by someone driving on 

the shoulder.3 With a complete absence of any indication of where the draw bar came 

from, Sumaya is simply unable to identify circumstantial evidence that makes any one of 

these scenarios more plausible than another. 

"Although proof of causation may be by direct or circumstantial evidence, it must 

be by 'substantial' evidence, and evidence 'which leaves the determination of these 

essential facts in the realm of mere speculation and conjecture is insufficient.' " 

(Leslie G., supra, 43 Cal.App.4th at p. 484.) The circumstances of Sumaya's injury are

undeniably tragic, but because there is no evidence of how the draw bar ended up on the 

freeway, it would be complete speculation and conjecture for any trier of fact to conclude 

 

3 In support of her argument that circumstantial evidence supports a finding that it is 

reasonably probable that the draw bar ended up on the freeway after disengaging from a 

receiver hitch, Sumaya lists several purported facts that are not supported by any 

evidence in the record other than that they appear in the portions of Jones's declaration to 

which the trial court sustained Cequent's objections. Moreover, some of those purported 

facts are contradicted by common sense or are completely speculative. For example, 

relying on the portions of Jones's declaration to which objections were sustained, Sumaya 

states that "the draw bar was too heavy to throw from the side of the road" and "[t]he 

draw bar is too heavy to have been kicked up from the side of the road because vehicles 

do not travel fast enough in the shoulder to allow for the occurrence." Sumaya also states 

that "[t]he draw bar is too heavy to bounce out of a vehicle[,]" but overlooks the 

possibility that the draw bar could have been placed on an unprotected part of a vehicle, 

such as a bumper, a roof or the edge of a flatbed truck or on top of a precariously-stacked 

load, and could have fallen off through subsequent freeway vibrations and bumps. 
17

that, because of a product defect, the draw bar disengaged from a receiver hitch on the 

freeway and injured Sumaya. 

To support her causation argument Sumaya cites several cases, but none of them 

are applicable because, in each, the plaintiff presented evidence from which a finder of 

fact could determine that it was reasonably probable that the defendant's alleged tortious 

conduct caused the plaintiff's injury, and was not just — as here — merely possible based 

on speculation. 

One of the cases on which Sumaya focuses most heavily is Chavez v. Glock, Inc.

(2012) 207 Cal.App.4th 1283, 1292 (Chavez). In Chavez, the plaintiff was accidently 

shot by his three-year-old son with a gun, and he alleged — among other things — that 

one cause of the accident was that the manufacturer did not design the gun with a trigger 

that required the application of more pressure than a small child would be able to apply. 

Chavez concluded that the issue of causation should be tried to a jury rather than resolved 

on summary judgment because it was not unduly speculative whether the accident could 

have been prevented by a different trigger design. Chavez explained that although direct 

evidence was not available about how the child fired the gun, "it is neither impossible to 

prove causation nor is proof on this issue necessarily speculative" because "[t]he hand 

size and grip strength of children are readily measurable[,]" and "a child's ability to pull a 

trigger of various trigger pull strengths is measurable." (Id. at p. 1307.) As Chavez

pointed out, based on that evidence "[a] jury could reasonably infer from this information 

whether a heavier trigger would have reduced or avoided the risk of harm in this case."

(Ibid.) Here, in contrast, because of the complete absence of evidence regarding how the 
18

draw bar ended up on the freeway, it is it impossible for Sumaya to prove whether her 

injury could have been prevented had Cequent designed the tow hitch assembly 

differently or provided a warning. Unlike in Chavez, this is a case in which "it is . . .

impossible to prove causation" and "proof on this issue [is] necessarily speculative"

(Ibid.)

Similarly, Sumaya relies on Campbell v. General Motors Corp. (1982) 32 Cal.3d 

112 (Campbell) for its statement that " '[i]t is not incumbent upon a plaintiff to show that 

an inference in his favor is the only one that may be reasonably drawn from the evidence; 

he need only show that the material fact to be proved may logically and reasonably be 

inferred from the circumstantial evidence' " (id. at p. 121, italics added), and that "[t]o 

take the case from the jury simply because the plaintiff could not prove to a certainty that 

the device would have prevented the accident" is improper (ibid., italics added). 

However, Sumaya overlooks the crucial difference between this case and Campbell, 

namely the presence of circumstantial evidence relating to the cause of plaintiff's injury. 

In Campbell the issue was whether the plaintiff, who was injured when riding a bus, 

could establish that her injury could have been prevented had the manufacturer installed 

handrails inside the bus. There was ample evidence of the details of the accident. 

"Plaintiff testified that she was injured when thrown from her seat to the floor on the 

opposite side of the bus. She further testified that before falling she reached out with 

both arms for something to hold on to, but nothing was there. Given plaintiff's position at 

the time the bus turned, a jury could reasonably infer from the evidence that a handrail or 

guardrail within her reach would have prevented the accident. Although this fact may not 
19

be capable of mathematical proof, it is nevertheless a reasonable inference that may be 

drawn from the evidence." (Id. at p. 122.) In Sumaya's case, in contrast, the crucial 

details of how the draw bar ended up on the freeway are not known. Therefore, the issue 

is not simply whether Sumaya has to prove to a certainty or with mathematical proof that

her injury was caused by a product defect in the tow hitch assembly. Instead, unlike in 

Campbell, the issue is whether, without any evidence at all of how the draw bar ended up 

on the freeway, a jury can be allowed to speculate as to causation. As we have explained, 

case law is clear that to establish causation a plaintiff must rely on more than speculation, 

conjecture or mere possibility. (See Bowman, supra, 186 Cal.App.4th at p. 314

[concluding that the plaintiff did not establish that a reasonable jury could have 

concluded that allegedly defective brakes were "the probable cause of the accident"

because "although proof of causation may be by circumstantial evidence, it must be by 

' "substantial" evidence, and evidence "which leaves the determination of these essential

facts in the realm of mere speculation and conjecture is insufficient" ' "].)

Finally, Dimond v. Caterpillar Tractor Co. (1976) 65 Cal.App.3d 173 (Dimond) is 

another case that Sumaya relies on, but which is inapposite because the plaintiff in that 

case — unlike here — was able to identify circumstantial evidence showing that 

plaintiff's theory of how the accident occurred was not only possible, but the most 

probable explanation of what occurred. Specifically, in Dimond the plaintiff worked in a 

warehouse where heavy paper rolls fell onto him, and he was found on the ground next to 

a forklift that he had been assigned to operate. (Id. at pp. 177-178.) Although the 

plaintiff had amnesia due to his injuries and there were no other witnesses to the accident, 
20

the plaintiff contended that the accident happened while he was operating a forklift 

manufactured by the defendant, and that because of an ambiguous warning on the 

forklift's protective cage that it would not withstand heavy loads, he bolted from the cage 

rather than staying protected inside the cage when the paper rolls began to fall on him. 

(Id. at p. 181.) The defendant argued that the plaintiff could not prove causation because 

it was possible that the plaintiff was not operating the forklift when the paper rolls fell on 

him, as he simply may have been standing near the forklift when the paper rolls began to 

fall. Dimond concluded that "[t]here was sufficient circumstantial evidence from which 

the jury could reasonably infer that plaintiff bolted [from the forklift] when he saw the 

stack of paper falling and was struck as he was trying the flee the machine" (ibid.), and, 

moreover, that plaintiff's theory was the most probable scenario.4 Based on the 

circumstantial evidence, Dimond concluded that although "[t]here may be other possible, 

though hardly probable, explanations why plaintiff was where he was when struck by the 

stack of paper[,]" "[t]he known facts and circumstances most strongly suggest that 

plaintiff was in the [forklift] but abruptly abandoned it when the rolls of paper began 

falling." (Id. at p. 182, italics added.) In such a case, "[t]he mere fact that other 

inferences adverse to plaintiff might be drawn does not render the inference favorable to 

 

4 As Dimond explained the circumstantial evidence supporting its conclusion, 

shortly before the accident the plaintiff had been instructed to transport some paper rolls; 

the forklift was found near where such paper is stored; the forklift was in neutral gear 

with the engine still running; plaintiff always turned off the engine when dismounting the 

forklift; there was a dent in the forklift's protective cage after the accident which was not 

present earlier; and plaintiff was found face down near the back of the forklift with his 

feet closest to it. (Dimond, supra, 65 Cal.App.3d at p. 182.) 
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plaintiff too conjectural or speculative for consideration." (Ibid.) Here, in contrast, the 

circumstantial evidence does not point to a single explanation for the draw bar ending up 

on the freeway that is more probable than other possible explanations, and thus any such 

inference would be too speculative to support a causation finding. This is simply not a 

case like Dimond, or the others cited by Sumaya, in which "[t]he known facts and 

circumstances most strongly suggest" that Sumaya's theory of how the draw bar came to 

be located on the freeway is the most probable explanation. (Ibid.)5 

In sum, we conclude that because Sumaya was unable to identify any admissible 

evidence that would allow a jury to reach a reasonable inference that the draw bar most 

probably came to be located on the freeway after disengaging from a receiver hitch, or 

due to any other failure of the tow hitch assembly, Sumaya failed to meet her burden of 

showing that a triable issue of material fact existed on the element of causation for both 

of her causes of action. Accordingly, the trial court properly granted summary judgment 

in favor of Cequent. 

 

5 Sumaya cites Vandermark v. Ford Motor Co. (1964) 61 Cal.2d 256 and Elmore v. 

American Motors Corp. (1969) 70 Cal.2d 578 for the proposition that causation that a 

product defect caused an injury may be proven by circumstantial evidence when direct 

evidence is not available. However, those cases, just like Chavez, Campbell and Dimond, 

do not advance Sumaya's argument because the problem here is not simply that direct 

evidence is unavailable. Instead, in this case, even when the circumstantial evidence is 

considered, there is simply no basis for an inference that it is more likely than not that the 

draw bar ended up on the freeway because it disengaged from a receiver hitch. 
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DISPOSITION

The judgment is affirmed. In the interests of the justice, the parties shall bear their 

respective costs on appeal. (Cal. Rules of Court, rule 8.278(a)(5).)

IRION, J.

WE CONCUR:

BENKE, Acting P. J.

MCDONALD, J.