Filed 5/10/16 Timmerman v. Lambert CA2/1
                  NOT TO BE PUBLISHED IN THE OFFICIAL REPORTS
California Rules of Court, rule 8.1115(a), prohibits courts and parties from citing or relying on opinions not certified for
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              IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA

                                     SECOND APPELLATE DISTRICT

                                                  DIVISION ONE


PAUL TIMMERMAN,                                                      B262465

         Plaintiff and Respondent,                                   (Los Angeles County
                                                                     Super. Ct. No. GC045518)
         v.

CAROLE ANN LAMBERT,

         Defendant and Appellant.



         APPEAL from a judgment of the Los Angeles Superior Court, C. Edward
Simpson, Judge. Reversed and remanded.
         Inglis, Ledbetter, Gower & Warriner, Rhett P. Warriner, Richard S. Gower for
Defendant and Appellant.
         DeWitt Algorri & Algorri, Ernest P. Algorri, Sam S. Soleimany for Plaintiff and
Respondent.
                                            _____________________
       Riding his bicycle shortly before sunrise, plaintiff and respondent Paul
Timmerman collided with the right-front portion of defendant and appellant Carole Ann
Lambert’s car as Lambert was turning left at a residential intersection. In Timmerman’s
suit for personal injury damages, the trial court granted each party’s motion to exclude
the testimony of the other’s accident reconstruction expert. Lambert appeals from the
judgment in Timmerman’s favor, contending that the trial court’s exclusion of her
accident reconstruction expert’s testimony was an abuse of discretion. We conclude that
the trial court erred in excluding certain portions of the expert opinion evidence proffered
by Lambert, and that the error had a likely impact on the jury’s verdict. We therefore
reverse the judgment.

                                       Background
       Timmerman sued Lambert for damages resulting from injuries he incurred when
the bicycle he was riding collided with her car, shortly before dawn on September 30,
2009, in Altadena, California.
The Accident
       Sunrise on the morning of September 30, 2009, was at 6:47 a.m. Lambert testified
that it was still dark as she drove north on Midlothian Drive in a residential neighborhood
of Altadena with her headlights on, on the way home from her gym shortly before 6:30
a.m. Activating her car’s left turn signal, Lambert turned left onto Meadowbrook Road,
cutting the turn short. She believed she was driving going somewhat slower than the
posted 25 mile-per-hour speed limit, about 20 miles per hour, as she made the turn.
       Lambert saw no southbound vehicle or headlights approaching. When she heard a
loud thump on the right side of her car as she turned, she realized she had been in an
accident. She stopped her car immediately, and found Timmerman and his bicycle in the
road next to the right side of her car. Lambert’s car sustained damage to its right front
fender, hood, and windshield, rendering it a total loss. Timmerman was seriously injured,
and his bicycle sustained major damage.




                                             2
       Timmerman testified that he was on a twilight exercise ride that morning,
something he did before work a few times a week. His bicycle—a carbon-fiber and
aluminum road bike with a $7,000 retail value—had no light and no reflectors. When he
left his house about five or 10 minutes before the accident, the sky was not dark, but was
“twilight” blue; “there [was] no spectral light coming down and creating hard shadows.”1
       He approached the intersection where the collision occurred going south on
Midlothian Road, slightly downhill around a gradual curve to the right. According to the
investigating police officer, Timmerman said his approximate speed was 30 miles per
hour. He testified that his bicycle’s computer device recorded his speed as 22 miles per
hour at the time of (or up to three seconds before) the collision.
Lambert’s Accident Reconstruction Expert
       On November 24, 2014, plaintiff’s counsel deposed Jon Landerville, an expert
designated to testify on Lambert’s behalf on issues of accident reconstruction.
Landerville had a Bachelor of Science degree in mechanical engineering with a minor in
applied mathematics, and a Master of Science degree in mechanical engineering. He is a
California registered engineer, accredited by the Commission for Traffic Accident
Reconstruction. He had worked in the field of forensic engineering for about 24 years,
had been involved in more than 3,000 accident reconstruction projects (including
accidents involving automobiles and bicycles), and had testified in hundreds of
depositions.
       At his deposition Landerville found the bicycle tire abrasions and damage to the
bicycle to be consistent with an approach speed of 25 to 30 miles per hour. And he
testified that Lambert could not have been traveling faster than about 15 to 17 miles per
hour (notwithstanding her testimony that she might have been 20 or more miles per
hour), judging from the distance between the point of impact and where Lambert’s car
stopped.




       1
           At trial Timmerman testified he left his house at approximately 6:15 a.m.

                                              3
Motion In Limine To Exclude Landerville’s Testimony, And Evidence Code Section
402 Hearing
       Two days before the trial’s scheduled commencement, Timmerman moved in
limine to exclude Landerville’s testimony and exhibits; or in alternative, seeking a
hearing on a motion to exclude the evidence under section 402 of the Evidence Code.
The motions argued that Landerville’s opinion testimony—regarding the speeds of the
bicycle and car, that safe riding required use of a light on Timmerman’s bicycle, and that
Lambert would have seen him if he had a light on his bicycle—lacked foundation, were
contrary to the evidence, and would mislead or confuse the jury; and that his photos,
diagrams, and videos lacked foundation and were speculative and irrelevant because they
“represent a complete absence of substantial similarity of conditions, times and events.”
       On the day the trial commenced, the trial court held a section 402 hearing on the
admissibility of Landerville’s proposed testimony and exhibits. Timmerman’s counsel
summarized the parties’ respective contentions: The plaintiff contends that the case
involves a simple left-turn collision during daylight; Lambert contends the collision
involved “a conspicuity issue,” involving Timmerman’s visibility to Lambert, because
the collision occurred during nighttime.
       According to Timmerman’s counsel, his first motion addressed Mr. Landerville’s
proposed testimony about the speeds of the bicycle and the car, whether the bicycle
should have had a light, and whether Timmerman was visible and “conspicuous” to
Lambert. His second motion sought exclusion of Landerville’s reenactment video
(apparently showing the site with an approaching bicyclist). The court indicated at the
outset that “if Mr. Landerville falls on any of the items” in the first of these motions, the
second motion is moot.
       The trial judge viewed Landerville’s photographs and stated he had read
Landerville’s deposition testimony. Landerville proposed to testify that the conditions of
the respective vehicles after the collision indicate the bicycle was travelling roughly 18 to
20 miles per hour or slightly faster, perhaps 20 to 22 miles per hour, when it hit
Lambert’s car; and that its approach speed before braking was somewhat faster, between


                                              4
25 and 30 miles per hour. Landerville also proposed to testify, based on the investigating
police officer’s accident-site measurements, that Lambert’s car must have been traveling
slower than the 20 to 25 miles per hour Lambert had estimated at the time of the accident.
And he proffered photographic evidence of the accident site: (1) showing the layout of
the intersection and the curvature of the road, with their exposure calibrated to accurately
show the degree of light (artificial and natural) on the day of the year and time of the
morning shown by other evidence to have been the time of the accident; and (2) showing
what Timmerman’s approach would have looked like from Lambert’s position (based on
estimates of the vehicle’s speeds) at the time of the accident, both without, and with a
light on the bicycle.2
       After hearing testimony from Landerville and reviewing his deposition, his
qualifications, and his exhibits, the court expressed its complete satisfaction with
Landerville’s background, training and extensive experience in the field of accident
reconstruction. Explaining that its ruling should not reflect on Landerville’s extensive
expertise or experience, however, the trial court precluded Landerville’s testimony in its
entirety.
       With respect to its exclusion of Landerville’s opinions about the vehicles’ speeds,
the court offered a number of explanations: “I don’t believe expert testimony on relative
speeds are important. The jury is going to hear testimony from the participants as to the
speeds that they thought that they were going. The jury is free to accept or reject that
testimony.”
       To the extent Landerville based his testimony about the vehicles’ speeds on their
conditions after the crash, the court found that “the particular field here of a bicycle
colliding with a motor vehicle has not been the major subject of Mr. Landerville’s

       2
         Landerville and his assistant had taken photographs of the site to reflect the
lighting conditions at the time of the accident, and what a driver in Lambert’s position
could and could not have observed. His photographs were scientifically prepared using a
grayscale in order to simulate the lighting with the sun in the same position as it was
between 6:24 a.m. and 6:28 a.m. on the date and at the accident’s likely times, as shown
by the uncertain (and somewhat disputed) evidence.

                                              5
experience, training or background and a substantial number of his opinions are
speculative in these areas and not supported by adequate science.”
       With respect to Landerville’s testimony about the distance at which Lambert could
have observed Timmerman’s approach (without and with a bicycle light), the court held
that “the place where [Lambert’s car] came to rest” after the collision provides no
foundation from which to determine the car’s speed (and from that to compute the
distances between the vehicles at various times before the collision). According to the
court, that is because the “Jaguar came to rest where the driver chose to stop the vehicle,”
rather than because it collided with an immovable object.3
       With respect to exclusion of Landerville’s testimony about accident-site lighting at
the time and conditions on the morning of the collision, the court explained: “One of the
disputed issues in the case is whether or not . . . the defendant observed the plaintiff. I
don’t believe that that is an issue upon which expert testimony can be used or relied
upon. There are so many, many, many variables. It depends upon the light, the time of
day, whether the sun was in somebody’s eyes, where the driver of the vehicle was
looking. Were there any distractions that caused the driver to be distracted. Was the
bicycle ridden in the middle of the lane, closer to the curb, on the lane divider on
Midlothian. All of those things a jury is going to have to sort out and decide. And I
don’t believe that expert testimony is relevant or helpful in having the jury make that
decision. An expert attempting to testify to those disputed issues has the potential of
removing those issues from the jury, that properly belong with the jury.”4


       3
        The transcript reflects the court’s statement that the car did not collide with “a
removable object,” which—although phonetically similar to “immovable object”—would
make little sense.
       4
        When discussing the relevance of Landerville’s testimony on the issue of
Lambert’s ability to observe Timmerman’s approach, and the ability of the jury to
determine whether Timmerman was visible to Lambert, the court did not mention
Landerville’s deposition reference to studies showing that bicyclists believe they can be
seen by approaching cars at twice the distance that automobile drivers believe they can
see bicyclists.

                                              6
       The court went on to explain that the “simulations, the photographs of an effort to
depict the light or ambient light on a day in 2009 based upon a day in 2010 or later is just
not reliable.” It explained: “There is so much that ambient light depends upon. The
visibility depends upon the cloudiness of the sky. The intensity of the sun. You may
well be able to identify the position of the sun in the sky, but I don’t think we are able to
quantify the intensity of the light, any clouds or other shade in the area. It’s going to be
up to the jury to decide whether or not the plaintiff was or was not visible based upon the
testimony of the—of the participants.”5
       After the court ruled that Landerville’s evidence would be excluded in its entirety,
Lambert’s counsel made an oral motion to exclude Timmerman’s accident reconstruction
expert from testifying. The court granted the oral motion to exclude the photographs
taken by Timmerman’s expert purporting to show the ambient light and Lambert’s field
of vision at the time and on the date of the accident, in order to be “consistent” in its
rulings.
Trial and Judgment
       The jury found unanimously that Timmerman suffered substantial damages, and
that Lambert’s negligence was a substantial factor in causing his harm. The jury also
found (10 to 2) that Timmerman was not negligent. Lambert filed a timely appeal from
the resulting judgment.6
                                          Discussion
       Lambert argues in this appeal that the trial court abused its discretion by excluding
Landerville’s evidence and testimony concerning the parties’ relative speeds, and
Lambert’s ability to see Timmerman as Timmerman approached the collision site—
before sunrise, at 25-or-more miles per hour without a light. Timmerman argues in


       5
         The trial court did not address Lambert’s objection to the untimeliness of the
plaintiffs’ motions, having been “served on me on Sunday afternoon before the Monday
morning trial . . . .”
       6
           Timmerman filed no cross-appeal.


                                              7
response that the trial court acted within its discretion in excluding Landerville’s
testimony, because his opinions lacked foundation; they were based primarily on
speculation, unsupported assumptions, and conjecture; they were contradicted by the
testimony of percipient witnesses; and they would have been confusing to the jury.
       Evidence Code section 801 provides that the opinion testimony of an expert “is
limited to such an opinion as is: [¶] (a) Related to a subject that is sufficiently beyond
common experience that the opinion of an expert would assist the trier of fact; and
(b) Based on matter (including his special knowledge, skill, experience, training, and [¶]
education) 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, unless an expert is precluded by law from using such matter as a basis for his
opinion.”
A. Standard of Review
       The trial court’s decision to admit or exclude evidence, whether upon motion in
limine or following an Evidence Code section 402 hearing, is reviewed for abuse of
discretion. (People v. Williams (1997) 16 Cal.4th 153, 196-197; Pannu v. Land Rover
North America, Inc. (2011) 191 Cal.App.4th 1298, 1317.)
B. The Trial Court Abused Its Discretion By Excluding Landerville’s Expert
   Testimony and Evidence In Its Entirety
       1. The trial court erred by precluding Landerville’s evidence concerning the
            lighting conditions at the time and place of the accident.
       After acknowledging that Lambert’s ability to observe Timmerman’s approach at
the time and place of the accident is a significant disputed issue for the jury’s
determination, the trial court ruled that it is not a subject “upon which expert testimony
can be used or relied upon,” because there are “so many, many, many variables.”7 In so

       7
         The court explained that its exclusion of Landerville’s evidence as the vehicles’
speeds did not rest on any deficiency in his expertise. “You spent a good deal of your
career in this area. My concern is not your experience so much, but what is out there in

                                              8
concluding the court abused its discretion in two respects. First, according to the
evidence, most of the variables cited by the court either did not exist at the time and place
of the accident, or were amenable to proof by other evidence. It is undoubtedly true that
the jury would be called upon “to sort out and decide” variables such as the light and the
time of day that the accident occurred; but it is not true that expert testimony on those
subjects would be categorically irrelevant, unreliable, or unhelpful to the jury.
       The trial court was of course correct that it would be impossible to establish that
the lighting conditions when Landerville’s photos were taken (on the same day of the
year and the same time before sunrise, in successive years after the accident) were
precisely identical to those when the accident occurred. But the court erred in concluding
that uncertainties would render the photos, and Landerville’s testimony about them, so
unreliable or confusing as to justify their categorical exclusion.
       First, the record dispels the existence or import of most of the variables that
concerned the trial court. The parties did not dispute that the collision occurred shortly
before sunrise on September 30, 2009, and they stipulated that sunrise was at 6:47 a.m. at
the accident site on that date (as reported on the United States Naval Observatory Web
site). Nor did they dispute that the sun was in the virtually identical position on the same
date and at the same time in each of the years following the accident.8 Timmerman
testified that the morning was dry and the sky was cloudless; no one said otherwise. And
almost by definition, before sunrise the sun shines in no one’s eyes and casts no shadows.
Nor was there evidence of any distractions; Lambert or Timmerman both testified where

the scientific community that one, is necessary for this case, and two, has scientific
support.”
       8
         Timmerman’s counsel confirmed this methodology for determining the lighting
at the time and date of the accident: “I can represent to the court, from year to year [the
position of the sun is the same]. Obviously from time to time, there is a difference. But
from year to year, the difference in the degree of the sun angle and whatnot, we have an
astronomer here who can probably talk about that, is little, if anything. And doesn’t
make an appreciable difference. . . . I think we can agree that on the day of the incident,
whether it was 2011 when [Landerville’s photos] were taken or 2013 when ours was
taken, that the angle of the sun would be the same. The times are what matter.”

                                              9
they looked as they approached the intersection; and Timmerman testified where in the
southbound lane he believed he rode as he proceeded down Midlothian toward the site of
the collision.
       Although the trial court found that these supposed variables preclude reliable
testimony concerning Timmerman’s visibility to Lambert during his twilight approach to
the accident site, they actually show the opposite. On the evidence before the trial court,
the jury could not have concluded that the sun cast shadows at the accident site, or that
clouds obscured the sun, or that the sun (or anything else) distracted Lambert or
Timmerman. The jurors could make their own determinations about whether the accident
occurred during “darkness” as defined by law. (Veh. Code, § 280 [“darkness” is “any
time from one-half hour after sunset to one-half hour before sunrise and any other time
when visibility is not sufficient to render clearly discernible any person or vehicle on the
highway at a distance of 1,000 feet”].)9 But whether the accident occurred during
“darkness” as legally defined would not inform the jury about the actual lighting
conditions at the time, date, and place of the accident. The jury had little or nothing to go
on to judge whether the light was such that a driver in Lambert’s position could have—or
should have—seen Timmerman’s approach. They therefore had little or nothing to go on
to judge whether the conditions were such that Timmerman was legally, or reasonably,
required to display a light or reflectors in order to enhance his visibility to oncoming
traffic. (E.g., Veh. Code, §§ 21201, 22350.)10




       9
        Timmerman testified that he believed he needed no light on his bicycle the
morning of the accident, although he said he left his house at about 6:15 a.m., during the
period of legal “darkness” more than one-half hour before dawn.
       10
          Vehicle Code section 21201, subdivisions (d)(1) and (e), provide that during
darkness, a bicycle or its rider must display a white light visible from a distance of 300
feet in front of the vehicle. Vehicle Code section 22350 provides that “[n]o person shall
drive a vehicle upon a highway at a speed greater than is reasonable or prudent having
due regard for . . . visibility . . . and in no event at a speed which endangers the safety of
persons or property.”

                                              10
       Yet these were perhaps the trial’s central disputed issues. Timmerman’s visibility
to Lambert at the time of the accident might well have a controlling impact on the jury’s
determination of the degree (if any) to which Lambert might (or might not) have been
negligent in turning left across Timmerman’s path; the degree (if any) to which either or
both of the parties might (or might not) have been negligent in driving or riding at the
speeds they did; the degree (if any) to which Timmerman might (or might not) have been
negligent in riding without a light before sunrise; and the degree (if any) to which any
such negligence on the part of either (or both) of the parties was a substantial factor in
causing the accident.
       Moreover, the admissibility of accident reconstruction evidence does not rest on
the ability to recreate the circumstances of the accident with exactitude. The conditions
on which the expert’s analysis rests must simply be “substantially similar” to those of the
actual occurrence. (Pannu v. Land Rover North America, Inc., supra, 191 Cal.App.4th at
p. 1318.) Photographs of the accident scene, although “highly pertinent” evidence
(People v. Turner (1990) 50 Cal.3d 668, 706) must be made under “substantially
similar”—but not necessarily identical—conditions. (Anello v. Southern Pacific Co.
(1959) 174 Cal.App.2d 317, 323.) “The standard that must be met in determining
whether the proponent of the experiment has met the burden of proof of establishing the
preliminary fact essential to the admissibility of the experimental evidence is whether the
conditions were substantially identical, not absolutely identical.” (Culpepper v.
Volkswagen of America, Inc. (1973) 33 Cal.App.3d 510, 521.) Here, although it was
impossible to establish that the conditions under which Landerville’s photos were taken
were identical to those at the time of the accident—on the same date and time but a year
or years later—neither is there evidence they were not. (Andrews v. Barker Brothers
Corp. (1968) 267 Cal.App.2d 530, 537 [similarity of conditions held to be sufficient
where no evidence showed dissimilarity].)
       Landerville testified in some detail to the scientific basis, documented in literature,
for his preparation of his photographs reflecting the site’s actual lighting conditions using
a grayscale to calibrate the exposure to match the actual lighting conditions at the site


                                             11
over the period of about five minutes during which the evidence showed the accident
might have occurred, and showing what Lambert would have been able to perceive with
and without a light on Timmerman’s bicycle. As with all expert testimony, Landerville’s
methods and exhibits were subject to cross-examination, impeachment, and critical
scrutiny by the jury. But nothing in the record indicates that his methods of calibrating
the photographs’ lighting to match the actual conditions represented any new innovative,
untested, or controversial methodology; and apart from the supposed variables identified
by the court, the trial court did not explain—and no reason is apparent—why testimony
and photographs prepared in the manner to which Landerville testified could not reliably
assist the jury in determining these critical issues. The court’s categorical exclusion of
this evidence is unsupported, and therefore abused the court’s discretion.11
       2. The trial court erred by categorically excluding Landerville’s calculation
            of Lambert’s maximum possible speed.
       The speeds of Lambert’s and Timmerman’s approach toward their collision site
might have been of significance at trial, for a number of reasons. Among other
possibilities, for example, the juror’s conclusions about the parties’ speeds might affect
evaluations of the vehicle’s distance apart and their visibility to one another leading up to
the collision; and it might affect the juror’s determinations whether either or both
vehicles were traveling faster than the posted 25 mile-per-hour speed limit, or faster than
was safe under the existing lighting conditions—issues relevant to their possible
negligence and causation of the collision. (Veh. Code, § 22350.)
       Lambert has not argued in this appeal that the trial court lacked justification for its
exclusion of Landerville’s opinions about the bicycle’s speed before and at the time of
the collision. Landerville had testified he drew his conclusions on those subjects from
photographs of the damage to the bicycle and the car, and from the bicycle’s tire showing
severe wear from a major skid, as well as from the police report. But the court concluded

       11
          The admissibility of any expert testimony or opinions offered by the parties in
any future proceedings in this case is not before us, and we express no opinion on those
subjects.

                                             12
that Landerville had not conducted the sorts of testing and examination that could provide
a foundation for his testimony on this issue. Landerville confirmed he had not evaluated
automobile-bicycle collisions involving bicycles of the same make, model, or precise
materials as those in Timmerman’s $7,000 carbon-fiber and aluminum bicycle. And he
supplied no basis for his claimed ability to judge Timmerman’s speed from the bicycle
tire’s wear during its skid as it approached Lambert’s car.
       Nor has Lambert argued that the court abused its discretion by ruling that the jury
would not be aided, and might be confused, by Landerville’s opinions about the time of
the collision, based on the extent of likely delays in contacting and routing the emergency
response between the time of the 911 call and the officers’ arrival at the accident scene.12
Because these aspects of Landerville’s testimony are not raised by Lambert’s appeal, we
have no reason to fault the court’s exclusion of the portions of Landerville’s testimony
that rest on these grounds.
       Landerville’s excluded testimony and evidence involved at least two additional
issues, however. The trial court’s exclusion of Landerville’s evidence in its entirety
excluded not only his opinions about the speed of Timmerman’s bicycle, but also his
opinions about Lambert’s speed approaching the collision site, and his photographic
evidence about the pre-dawn lighting conditions at the accident site during the period the
evidence showed the accident occurred.13
       Landerville testified that Lambert’s maximum possible speed at the time of the
collision could be determined by calculation, based on the distance between the point of
impact with Timmerman’s bicycle and the place the car stopped following the collision.

       12
          Lambert presumably would argue that the earlier the accident occurred, the
darker it was and the less-visible Timmerman would be approaching the accident site
without a light. As the trial court noted, the jury would have to decide whether a bicycle
light would have been helpful in making Timmerman visible at that time of the day.
       13
         Also excluded were Landerville’s testimony and evidence about the impact that
a standard bicycle light would have had on the visibility of Timmerman’s bicycle to an
approaching car, at the distances and lighting conditions shown by the evidence—issues
that Lambert’s appeal does not specifically address.

                                             13
He testified that Lambert’s car could not have been traveling as fast as the estimate
shown by some other evidence: “[I]f we look at the point of impact, it’s documented by
the officers on-scene. And the point of rest of the car. The car cannot be going 25 miles
per hour at that impact point, because it will never stop in time if you do the calculation
per perception and reaction and braking distance.” According to Landerville, if
Lambert’s car had been traveling at 25 miles per hour, it could not have stopped in less
than 100 feet—far more than the 32 feet measured by the investigating officers after the
accident. To stop in 32 feet, he computed, the car must have been traveling far slower—
perhaps 15 to 17 miles per hour, at most. And from evidence that Lambert’s car was
traveling more slowly than otherwise indicated, jurors might conclude (among other
possibilities) that the vehicles were further apart, and that Timmerman’s approach was
thus less visible to Lambert, when Lambert began her left turn across Timmerman’s path.
       The trial court did not agree with Timmerman’s counsel that the parties’ speeds
were of no importance—that the issue was only Lambert’s inattention, not the parties’
speeds. The court ruled instead that no reliable calculation of the speed of Lambert’s car
could be made based on the distance between the point of collision and where her car
stopped. “I don’t think it’s particularly reliable to use the place where the Jaguar came to
rest as a foundation for scientific analysis,” because the “Jaguar came to rest where the
driver chose to stop the vehicle,” not as a result of the collision.
       But according to Landerville—whose expert credentials the court confirmed—the
court’s reasoning ignored the undeniable fact that the distance in which a car can be
stopped is affected by its speed; if it is going faster, it cannot be stopped in as short a
distance as if it is going slower. But the court held to the contrary, that the distance it
took for Lambert to stop her car after the impact (shown by the investigating officer’s
measurements to be 32 feet) was totally voluntary on her part: “It could have been 42
feet or 52 or 12,” the court concluded. But according to Landerville, the court did not
understand the import of his calculations. “That’s the point,” he tried to explain; “the
brakes can’t stop the car at 12 feet” if it were going 25 miles per hour; at that speed its



                                              14
stopping distance would be 100 feet, when the driver’s perception and reaction time are
taken into account.
       We are instructed by Sargon Enterprises, Inc. v. University of Southern California
(2012) 55 Cal.4th 747, 770 (Sargon), that “under Evidence Code section 801, the trial
court acts as a gatekeeper to exclude speculative or irrelevant expert opinion.” It was
thus the trial court’s job to determine whether the matter relied upon by Landerville was
“of a type that reasonably may be relied upon by an expert in forming an opinion upon
the subject to which his testimony relates.” (Id. at p. 769.) Did the police report’s
measurements, scientific literature concerning driver perception and reaction times, and
mathematical calculations of automobile stopping distances based on speed and mass,
provide reasonable grounds for a qualified expert accident reconstruction engineer to
conclude that Lambert could not have stopped her car within 32 feet of the collision if she
had been traveling 25 miles per hour? Or to the contrary, was Landerville’s opinion on
that point based on speculation, conjecture, or propositions yet untested by scientific
evidence? (Id. at p. 770.)
       Although the trial court must exclude expert opinion testimony that is speculative
or based on matter or reasons that are unsupported by the material on which the expert
legitimately relies (Sargon, supra, at p. 772), “the gatekeeper’s role ‘is to make certain
that an expert, whether basing testimony upon professional studies or personal
experience, employs in the courtroom the same level of intellectual rigor that
characterizes the practice of an expert in the relevant field.’” (Ibid.) And although the
trial court has broad discretion to make that determination, its discretion is not unlimited.
“The discretion of a trial judge is not a whimsical, uncontrolled power, but a legal
discretion, which is subject to the limitations of legal principles governing the subject of
its action, and to reversal on appeal where no reasonable basis for the action is shown.”
(Id. at p. 773.)14

       14
         “The trial court’s preliminary determination whether the expert opinion is
founded on sound logic is not a decision on its persuasiveness. The court must not weigh
an opinion’s probative value or substitute its own opinion for the expert’s opinion.

                                             15
       The admonition that the trial court must exclude expert opinion testimony that is
speculative, or based on matter or reasons that are unsupported by the material on which
the expert legitimately relies, does not apply to Landerville’s opinion of Lambert’s
maximum possible speed. Timmerman’s counsel would be free to argue to the jury, and
the jury would be free to conclude (as apparently did the trial judge), that Landerville’s
opinion about the maximum possible speed of Lambert’s car should be distrusted and
rejected. But in this case the record lacks any evidence or indication that Landerville’s
opinion about the maximum possible speed of Lambert’s car was categorically
speculative, or that it was based on matter of a type on which an expert may not rely, or
on reasons that are unsupported by the material on which he relied in reaching his
conclusion.
       Nor was the trial court’s articulated basis for the opinion’s exclusion reasonable,
for it failed to account for the underlying logic: A driver can stop an automobile in no
shorter distance than is shown to be scientifically and mathematically possible with
respect to the automobile’s speed and characteristics; therefore the shorter the
automobile’s stopping distance, the slower the automobile’s speed. The trial court’s
ruling that the automobile’s maximum possible speed cannot be determined by a
qualified expert with sufficient reliability to assist the jury, based on the distance it took
to stop the car, therefore lacks any basis in the record. As the Supreme Court noted in
Sargon, the “issue before us is whether the court abused its discretion in excluding the
expert testimony” based on its conclusion that the opinion “was not ‘[b]ased on matter . .
. that is of a type that reasonably may be relied upon by an expert in forming an opinion




Rather, the court must simply determine whether the matter relied on can provide a
reasonable basis for the opinion or whether that opinion is based on a leap of logic or
conjecture. The court does not resolve scientific controversies. Rather, it conducts a
‘circumscribed inquiry’ to ‘determine whether, as a matter of logic, the studies and other
information cited by experts adequately support the conclusion that the expert’s general
theory or technique is valid.’ [Citation.] The goal of trial court gatekeeping is simply to
exclude ‘clearly invalid and unreliable’ expert opinion.” (Sargon, supra, at p. 772.)

                                              16
upon the subject to which his testimony relates . . . .’” (Sargon, supra, 55 Cal.4th at pp.
775-776.)15
       It was up to the jurors to decide whether they believed that Lambert’s speed was
important to their decision, and if so, what speed they believed she was traveling.
Despite the trial court’s contrary conclusion, there can be no doubt that any determination
of that disputed fact might be informed by Landerville’s conclusion (if credited), that
Lambert must have been going 15 to 17 miles per hour rather than the 25 miles per hour
indicated by other evidence, because otherwise her car could not possibly have stopped
where it did. It is not contended that Landerville’s computations and opinion about
Lambert’s speed would be within the common knowledge or experience of jurors. (New
v. Consolidated Rock Products Co. (1985) 171 Cal.App.3d 681, 692 [for an expert
witness’ opinion testimony to be admissible under section 801, it must relate to a subject
beyond common experience such that the expert’s opinion would assist the jury].) In the
absence of any basis in the record for its exclusion, Landerville’s opinion on that subject
was evidence that the jury might have found helpful, and that Lambert was entitled to
present. Its exclusion therefore abused the trial court’s discretion.
C. The Exclusion of Landerville’s Evidence Was Prejudicial
       “The trial court’s error in excluding evidence is grounds for reversing a judgment
only if the party appealing demonstrates a ‘miscarriage of justice’—that is, that a
different result would have been probable if the error had not occurred.” (Zhou v.


       15
          Timmerman argues that the court’s exclusion of Landerville’s opinion about
Lambert’s speed was justified because it relied on “indeterminate ‘approximate’
distances, because the collision report was ‘not to scale.’” But that misunderstands the
term “not to scale,” which means only that the report’s accident-site drawings may not
accurately match its measurements. And although the form recites on each page that its
measurements are “approximate,” it reports the “approximate” stopping position of each
of the car’s four wheels to the nearest foot, as measured by the investigating officer using
a “Rollameter” wheel—just as were the measurements relied upon by experts in other
accident cases (e.g., Pannu v. Land Rover, supra, 191 Cal.App.4th at p. 1304). This
record could not justify a categorical exclusion of any computations based on these
measurements, even if the trial court had accepted such a contention.

                                             17
Unisource Worldwide (2007) 157 Cal.App.4th 1471, 1480; Vorse v. Sarasy (1997) 53
Cal.App.4th 998, 1013; Cal. Const., art. VI, § 13; Evid. Code, § 354; Code Civ. Proc., §
475.)
        The excluded evidence was intended to better enable the jury to evaluate whether
either or both of the parties were negligent in approaching the site at speeds that either
exceeded the posted speed limit or were otherwise unreasonable under the circumstances;
in failing to display lighting that was legally or reasonably required under the
circumstances; or in failing to earlier observe the other, either for those or other reasons.
Without it, the jury had only Lambert’s testimony that it was still quite dark at the time of
the accident, and she could not see Timmerman’s approach; and Timmerman’s testimony
that he believed it was already quite light.
        The jurors were unanimous in finding that Lambert was negligent in turning left
across Timmerman’s path; we cannot say that a different conclusion would have been
reasonably probable if Landerville had been permitted to testify.
        However only 10 jurors found that Timmerman was not negligent in approaching
the accident site at the speed he did, without a light, and wearing the clothing he wore,
under the conditions at the time of the accident. If the jury had heard and seen evidence
from which it could evaluate the parties’ recollections and credibility concerning the
lighting and visibility at the accident site, and the distance at which Lambert could
reasonably be expected to see Timmerman’s approach, it seems reasonably probable that
two or more jurors might have concluded that Timmerman was negligent to some degree,
and that his negligence was a substantial factor resulting in his harm.

                                         Conclusion
        The trial court abused its discretion by excluding Landerville’s expert testimony in
its entirety, and particularly with respect to the issues identified above. Because it
appears reasonably probable that these errors affected the verdict and judgment, reversal
is required.




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                                       Disposition
      The judgment is reversed. The matter is remanded for appropriate pretrial
evaluation and determination of questions regarding admissibility of either party’s expert
opinion testimony in accord with this opinion.
      Appellant to recover her costs on appeal.
      NOT TO BE PUBLISHED.




                                                  CHANEY, J.


We concur:



             ROTHSCHILD, P. J.



             JOHNSON, J.




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