Present: All the Justices 

JEFFREY A. TITTSWORTH 

OPINION BY JUSTICE ROSCOE B. STEPHENSON, JR. 

v. Record No. 951742 

 September 13, 1996 

STEPHANIE N. ROBINSON 

FROM THE CIRCUIT COURT OF STAFFORD COUNTY 

Carleton Penn, Judge Designate 

 The sole issue in this appeal is whether the trial court 

erred in allowing certain expert testimony. 

 Jeffrey A. Tittsworth filed a motion for judgment against 

Stephanie N. Robinson seeking damages for personal injuries he 

sustained in a motor vehicle collision. The case was tried to a 

jury which returned a verdict in favor of Robinson. The trial 

court entered judgment on the verdict, and this appeal ensued. 

 At the time of the accident, Tittsworth, operating his Mazda 

van, was leaving a parking lot adjoining Highway Route 610 in 

Stafford County. While stopped at the lot's exit and waiting for 

traffic on the highway to clear, a Hyundai automobile operated by 

Robinson struck the rear of the Mazda. 

 Rain had been falling that day, and the soles of Robinson's 

tennis shoes were wet. Robinson's car struck the rear of 

Tittsworth's van when, as Robinson leaned over to move some 

curling irons from the front passenger seat to the floor of her 

car, her foot slipped off the clutch pedal. 

 At the accident scene, Tittsworth told Robinson that he had 

not been injured. However, several hours after the collision, 

Tittsworth began to experience stiffness in his back which became 

painful and progressively worse, and, two days later, he saw a 
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physician. After undergoing a Magnetic Resonance Imaging (MRI) 

scan of the lumbar spine, Tittsworth was referred to Dr. Donald 

G. Hope, a neurosurgeon. 

 Dr. Hope found that Tittsworth had a herniated disk at the 

"L5-S1 level." Based upon Tittsworth's medical history, the 

doctor concluded that the herniated disk in Tittsworth's lumbar 

spine resulted from the collision. 

 Robinson presented two expert witnesses in an effort to 

prove that the collision could not have caused Tittsworth's disk 

to rupture. Alfred L. Cipriani was qualified as an expert in the 

field of mechanical engineering and gravity acceleration impact 

analysis. Dr. Peter H. Abbrecht was qualified as an expert in 

biomedical engineering and biomechanics. 

 Cipriani testified that so-called "G force" is the 

acceleration of gravity, which, he explained, accelerates at 32.2 

feet per second, constituting one G. Cipriani concluded that the 

force experienced by Tittsworth in the collision was not greater 

than 1.6 G's and that such force is less than many people 

experience in daily activities.1

 Cipriani then explained how he reached his conclusion. He 

first obtained the identification numbers of the two vehicles 

involved in the collision. From these numbers, he ascertained 

the make, model, and year of each vehicle. With this 

 1Cipriani testified that a person, in hopping off an eightinch step, would subject his head to as much as 8 G's and, in 

coughing, would subject his head to three and one-half G's. 
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information, he had "a data base available which provide[d] 

vehicle information such as the wheel base, the overall width, 

the weight of the car, things like that, so [he could] identify 

the vehicle more specifically." Cipriani then "look[ed] up crash 

tests data on substantially similar cars." These tests are 

conducted by organizations such as the National Highway 

Transportation Safety Administration, the Insurance Institute for 

Highway Safety, and Transport Canada, and they reveal how "stiff" 

a vehicle is in the front and rear. According to Cipriani, 

"[t]he amount of crush that occurs to a vehicle for a given speed 

is dependent upon how stiff the vehicle is." He stated that, 

having obtained all this information, he then was "ready to look 

at the photographs [of the vehicles involved in the collision] 

and to start to do an analysis." 

 After looking at the photographs, Cipriani "assume[d] half 

of an inch of permanent crush [damage] of the whole width and 

whole height of the back of the [Mazda]." He also "assumed a 

half of an inch of crush damage over the width of the entire 

[Hyundai]." These assumptions, he said, gave "the benefit of the 

doubt" to Tittsworth. 

 Cipriani, utilizing the crash test information and his 

assumptions regarding crush damage, and with the assistance of a 

computer program which he did not develop, then calculated the 

maximum force that was applied to the rear of Tittsworth's van in 

the collision. This force, he determined, was 1.6 G's. 
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 Dr. Abbrecht testified that, in his opinion, "the force of 

this accident [was] not enough to cause any injury, and . . . 

definitely not enough to cause a specific injury of herniation of 

the L5 S1 disk." Before reaching this conclusion, Abbrecht had 

reviewed Tittsworth's medical records, including x-rays and the 

MRI scan of Tittsworth's lumbar spine, Tittsworth's deposition, 

photographs of the two vehicles, and Cipriani's analysis. He 

based his opinion in large measure on experiments, conducted by a 

concern called Engineering Dynamics Corporation, in which human 

volunteers were exposed to 2.2 G's of force in rear-end 

collisions. According to Abbrecht, the volunteers received no 

injuries in the experiments. These experiments, however, were 

designed to investigate neck injuries, not lumbar injuries, and 

Abbrecht conceded that there have been no "low back" studies. 

 Tittsworth moved the court to strike the experts' testimony. 

 He asserted, inter alia, that their testimony lacked an adequate 

foundation and a factual basis to support their opinions and that 

the experts relied upon experiments conducted under conditions 

that were not substantially similar to the conditions existing in 

the present case. The trial court denied the motion. 

 Generally, expert testimony is admissible in civil cases if 

it will assist the fact finder in understanding the evidence. 

Such testimony, however, must meet certain fundamental 

requirements. See Code §§ 8.01-401.1 and -401.3; Tarmac MidAtlantic, Inc. v. Smiley Block Co., 250 Va. 161, 166, 458 S.E.2d 
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462, 465-66 (1995); Lawson v. John Doe, 239 Va. 477, 482-83, 391 

S.E.2d 333, 336 (1990); Clark v. Chapman, 238 Va. 655, 664-65, 

385 S.E.2d 885, 891 (1989). Such testimony cannot be speculative 

or founded upon assumptions that have an insufficient factual 

basis. Tarmac Mid-Atlantic, Inc., 250 Va. at 166, 458 S.E.2d at 

466; see Gilbert v. Summers, 240 Va. 155, 159-60, 393 S.E.2d 213, 

215 (1990); Lawson, 239 Va. at 482-83, 391 S.E.2d at 336; Cassady

v. Martin, 220 Va. 1093, 1100, 266 S.E.2d 104, 108 (1980). Such 

testimony also is inadmissible if the expert has failed to 

consider all the variables that bear upon the inferences to be 

deduced from the facts observed. Tarmac Mid-Atlantic, Inc., 250 

Va. at 166, 458 S.E.2d at 466; see Swiney v. Overby, 237 Va. 231, 

233-34, 377 S.E.2d 372, 374 (1989); Grasty v. Tanner, 206 Va. 

723, 727, 146 S.E.2d 252, 255 (1966). Further, where tests are 

involved, such testimony should be excluded unless there is proof 

that the conditions existing at the time of the tests and at the 

time relevant to the facts at issue are substantially similar. 

Tarmac Mid-Atlantic, Inc., 250 Va. at 166, 458 S.E.2d at 466; 

Runyon v. Geldner, 237 Va. 460, 463-64, 377 S.E.2d 456, 458-59 

(1989). 

 While Code §§ 8.01-401.1 and -401.3 have liberalized the 

admissibility of expert testimony, we think the experts' 

testimony here fails to meet the fundamental requirements 

enumerated above. With respect to Cipriani, there was no showing 

that the crash tests relied upon were conducted under conditions 
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similar to those existing at the accident scene. More 

importantly, Cipriani never examined the vehicles involved in the 

collision; rather, he relied solely upon the photographs of the 

vehicles to determine the permanent crush damage thereto. He did 

not know whether the undercarriages of the vehicles had been 

damaged, and, if so, the extent thereof. Indeed, Cipriani simply 

"assumed" that each vehicle sustained a crush damage of one-half 

an inch. 

 Abbrecht relied, in part, upon Cipriani's conclusion. He 

also relied upon the photographs of the vehicles and the rear-end 

collision experiments. Again, there was no proof that these 

experiments were conducted under circumstances substantially 

similar to those existing at the accident scene. Moreover, the 

tests focused upon neck injuries, not lumbar spine injuries, and 

Tittsworth sustained an injury to a disk in his lumbar spine. 

 In sum, the challenged expert testimony is speculative, is 

founded upon assumptions lacking a sufficient factual basis, 

relies upon dissimilar tests, and contains too many disregarded 

variables.2 Consequently, we hold that the testimony is 

unreliable as a matter of law, and, therefore, the trial court 

 2Robinson contends that Tittsworth "`opened the door' to the 

biomechanical evidence and waived objections to its 

admissibility" because Tittsworth's expert, Dr. Hope, testified, 

without objection, that a lumbar disk can rupture as a result of 

"the normal biomechanical factors that a person goes through 

. . . with standing, sitting, rotating from side to side without 

any trauma." We reject this contention. We do not think that 

such a general statement by a medical expert opened the door to 

the speculative and unreliable testimony of Robinson's experts. 
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erred in admitting it.3

 Accordingly, we will reverse the trial court's judgment and 

remand the case for a new trial. 

Reversed and remanded. 

 

 3On appeal, Robinson advances a harmless-error argument in 

asserting that the jury "could have rendered its decision without 

considering the [challenged] expert evidence." Robinson contends 

that the jury "could easily have found that [her] conduct was not 

negligent" or "could have reached its verdict based on [other] 

causation testimony." We reject this argument because we have no 

way of determining what evidence may have influenced the jury in 

reaching its verdict. See, e.g., Ring v. Poelman, 240 Va. 323, 

328, 397 S.E.2d 824, 827 (1990); Doe v. Thomas, 227 Va. 466, 473, 

318 S.E.2d 382, 386 (1984).