Cross-examining the accident reconstructionist.

Most auto collisions are uncomplicated: One car rear ends another, a car runs a stop fight, a driver leans down to turn on the radio and crosses the center line. Everyone agrees about what happened. The real issue is how badly someone was hurt.

There are, however, collisions involving conflicting witness accounts or physical evidence inconsistent with witness statements. Then, the trial centers on a factual dispute as to how the crash occurred. In these cases, expert accident reconstructionists are called on to render opinions as to the mechanics of the collision. These experts testify based on their interpretations of factual data or assumptions as applied to mathematical equations. The testimony can be pivotal in the outcome of a case. Therefore, the ability to effectively cross-examine an opponent's accident reconstructionist can be critical.

The threshold question for any expert testimony is admissibility. Opinion testimony is governed by Federal Rules of Evidence 702 and 703. Rule 702 states that "[i]f scientific, technical, or other specialized knowledge assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education, may testify thereto in the form of an opinion or otherwise." In determining the admissibility of accident reconstruction expert testimony, the obvious first question is whether the witness is an expert.

In 1985 the National Highway Traffic Safety Administration provided a grant to develop minimum criteria for the training of police traffic accident reconstructionists. From that grant grew the Accreditation Commission for Traffic Accident Reconstruction. The commission developed a training and accreditation process to certify qualified accident reconstructionists. As of 1994, 46 percent of those who took the exam failed on the first attempt, 35 percent on the second, and 46 percent on the third. No retests are allowed after the third try.(1) Many reconstruction witnesses do not hold this accreditation.

Accreditation is an important criterion in selecting an expert for the plaintiff's case in chief. Cross-examining an unaccredited opposition expert is not persuasive if the plaintiff's witness is also unaccredited.

Notwithstanding the criteria for training and accreditation, courts have allowed people with little or no understanding the physics or engineering principles involved to testify in this complex subject area.

Rule 703 provides that the testimony offered by expert witnesses must be of a type reasonably relied on by experts in the same scientific field. As a condition of admissibility, the trial judge must ensure that scientific evidence is reliable. This requires a judicial assessment of "whether the reasoning or methodology underlying the testimony is scientifically valid."(2) As the court's scientific knowledge usually be modest, at best, lawyers for the parties must show why the "reasoning and methodology" is or is not scientifically valid.

Once the threshold question of general admissibility, is met, Rule 703 requires "the opinion of the expert witness must be based upon proved or assumed facts which are [legally] sufficient to form the basis for [his or her] opinion."(3) The facts or data upon which an expert bases an opinion need not be independently admissible if "of a type reasonably relied upon by experts in the particular field in forming opinion or inferences upon the subject."(4) But when an expert's opinion is based on facts not admissible in evidence, the court must make the preliminary determination as to whether the data is of the kind others in the field reasonably rely on in reaching conclusions.(5)

An expert's testimony must be excluded if the court finds that the facts the expcert relied on are doubtful or in controversy that there is insufficient factual foundation to render a reasonably accurate conclusion, or that the probative value of the expert's opinion is substantially outweighed by the risk of testimony that would mislead the jury.(6)

If a court determines that an opinion based on inadmissible evidence is admissible, the question becomes, "Can that expert testify about the substance of the information relied on, converting inadmissible evidence into substantive evidence?" The notion of an expert as an inadmissible "hearsay conduit" to a jury is a subject of debate within the legal community.(7) Some jurisdictions liberally interpret Rule 703, allowing experts to bring into evidence otherwise inadmissible documents that support their opinions, without significant restriction.(8) Other jurisdictions strictly scrutinize the introduction of background documents, allowing the opinion while excluding introduction of otherwise inadmissible documents and testimony.(9)

Assuming the introduction of an opponent's expert accident reconstruction testimony, the focus of analysis must shift to cross-examination. Juries may not disregard expert opinions.(10) Further, the fact that the reconstructionist's testimony may conflict with an eyewitness's testimony does not make it inadmissible where the court finds it of help to a jury in understanding complex issues.(11) Therefore, the trial attorney, should use cross-examination to persuade the jury that the expert's testimony is wrong or unreliable.

Careful Analysis

Preparing for the cross-examination of an opponent's accident reconstructionist requires a thorough understanding of one's own case, the expert's interpretation of the physical evidence (for example, the type of skid mark), the associated scientific principles, and the expert's methodology. The cross-examiner must understand the foundation that the expert has or should have available to the development of the opinion and the validity of the expert's interpretation of the evidence. This requires scrutiny of all the facts that would or should have been available to that expert.

The accident reconstructionist will interpret physical evidence and apply data or assumptions to accepted mathematical equations to reach a conclusion. Although accident reconstruction is based on scientific principle, most of the principles are applied using empirical factors critical to the conclusions so that the opinions rendered are far from hard science. Experts make many assumptions with respect to the formulas, and experts emphasize facts favorable to the side that retained them.

The questions the reconstructionist will address will involve the results of the accident, such as damage to the vehicles, injuries to the occupants, skid marks, gouges in the road, accident debris, and resting positions of the vehicles after colliding or running off the road. How precisely a qualified reconstructionist can determine the mechanics of a given collision depends on the reliability and completeness of information available to that expert. With insufficient or unreliable information nobody, however astute, can produce more than vague speculation about the events of the accident.(12)

The lawyer must gather all information relating to the collision: the manufacturer's specifications for the vehicles involved, police reports, witness accounts, photographs of vehicles, reports of weather conditions at the time of the collision, reports prepared for the department of motor vehicles, estimates of damage, reports of all emergency medical technicians, photographs of the entire accident scene, photographs taken by the insurance investigators, newspaper articles and photographs of the accident, road maintenance records from the municipality to determine road composition and condition, and surveys of the area to determine the grade of the roadways. All the information should be independently verified to the extent that this is possible.

It is not sufficient to trust the facts and conclusions developed by the witnesses and police investigators. This is particularly, important regarding point of impact. Skid marks do not necessarily have precise starting and stopping points. How the investigators interpret the shadow lines at the outset of the skid marks will definitively control how the marks are measured. The marks may be produced by breaking or yawing.(13) Whether the marks represent multiple-wheel braking further affects their use in the reconstruction. Also, vehicles with antilock brakes leave different skids (typically lighter) than those that are equipped with conventional brakes.

Reconstructionists sometimes assume coefficients of friction (the amount of friction between the tires and the pavement) and do not perform an accurate skid test at the scene. However, scientific analysis has established that this approach is flawed. Dr. James Wambold, director of the Vehicle/Surface Interaction and Safety Program for the Pennsylvania Transportation Institute, has found serious limitations when using estimates of tire/pavement coefficients of friction, resulting in large errors in estimating king distances or initial speeds of vehicles involved in accidents.(14) Further, other variables such as braking effectiveness (in trucks), the character of or change in the road surface, or oil or ice and snow on the road will affect the coefficients of friction.

Eyewitness Angle

Often, reconstructionists assume eyewitness estimates of speed in their analysis. These estimates are fraught with error. These witnesses must be scrutinized as to their ability to accurately estimate the speed. What was their vantage point? How long did they see the vehicle? What is their experience with estimating speed, How does their eyewitness testimony match up with the physical evidence?

Experts also use eyewitness testimony with respect to locations of vehicles and their relationships to each other. Again, this testimony is fraught with error. The same scrutiny must be applied to every subjective analysis by eyewitnesses.

Reconstructionists often use crush deformation and crumpling to estimate speed and angles of approach. This again requires interpretation and involves assumptions as opposed to facts. In addition, reconstructionists often base assumptions on photographs as opposed to actual inspection of vehicles. Photos taken by a family member or an insurance adjuster may simply be a gross image of part of a vehicle without the sufficient detail necessary for making accurate assumptions. Absent forensic photography, documenting virtually, every item of damage to a vehicle, these photographs are nothing more than gross estimates. The different assumptions that various experts make from these photographs validate the inherent inaccuracy in this data.

Once a lawyer has developed factual information as completely as possible, the next and most important step can be taken: analysis of the facts and determination of how they affect the principles underlying the reconstruction. With this knowledge, the lawyer can prepare a cross-examination to gain admissions relative to the plaintiffs case as well as identify fallacies in the opponent's analysis.

Generally speaking, when preparing the cross-examination, the attorney must analyze how the expert witness got to the opinion: Is the witness lying, or is there a flaw in the analysis? Is the witness mistaken? Why is the witness mistaken? Are any relevant facts missing? Was something withheld?

With careful preparation, it is possible to identify the fallacies of the expert's approach. Once it is determined which facts are conclusively proven, the analysis can focus on whether the expert is relying on facts or operating on inappropriate assumptions.

There is no need to deal with everything the witness said on direct examination or impeach everything that can be impeached. The key is to let the jury see that a witness is wrong. The approach will vary from case to case. Every witness is different; every case is different.

Many texts provide transcripts of great cross-examinations. However, no one can provide cookbook cross-examinations. Rather, the cross-examiner must understand the subject matter, the witness, and the jury's relationship to that witness, and must have the instinct to discover the weak points in the testimony under examination. The cross-examiner must also bear in mind the dangers inherent in questioning about the witness's area of expertise. In this regard, it may be helpful to enlist the aid of a qualified reconstructionist to recognize flaws in the witness's analysis.

There are various approaches that can be used in cross-examining an expert reconstructionist. Certainly, the easiest is to secure admissions that support the plaintiff's case, enhance the credibility of the plaintiff's witnesses, and verify the plaintiff's theory. Almost always, there are strong points in a case that the opposing side cannot deny. For example, the seriousness of the collision or that the plaintiff was seriously hurt should not be in dispute. To the extent that an expert witness opposes those points, the witness becomes an advocate as opposed to a "neutral" witness. That witness's credibility will then be in doubt.

To the extent admissions can be gained about the validity of the facts used by the plaintiff's reconstructionist, the cross-examiner has ratified important aspects of the plaintiffs case. The case may be further bolstered if through discovery it is established that the expert mill acknowledge the plaintiff's theory as a reasonable alternative. It is not necessary for the expert to admit that the theory applies to this case as long as he or she will acknowledge that the plaintiffs theory is viable.(15)

The opinion of the reconstructionist is derived from data or assumptions applied to mathematical equations. The strength of any conclusion is only as good as the underlying data used in the formula. If a reconstructionist is mistaken about the facts or their interpretation, the opinion will be faulty because the variable within the equation will be incorrect. The focus of the examination must be on any inaccurate facts or faulty interpretations of them. The strength of such m examination is directly proportional to how convincingly those underlying facts have been developed in the trial.

If the reconstructionist relies on facts that are in dispute, the cross-examination can be used to set up the argument for summation that the facts used as a basis for the reconstructionist's opinion are either not supported by the evidence or depend on differing accounts of the accident. The thrust of the cross then focuses on the jury's accepting a particular scenario. If an alternative scenario has been convincingly developed, the jury can easily disregard the expert's opinion.

When an equation variable requires information that is not available or the expert assures information and does not verify it, the opinion will only be as strong as the assumption. The cross-examination should show the jury that the witness has chosen to assume unproven information. More important, jurors must come to understand that the assumption is subject to serious error.

When the facts are not in dispute, it is still necessary to understand the "science" - to understand the limitations of any equation. Some formulas are very sensitive to a change in variables; others are not. In a given equation, the change of one variable may have little to do with the result; in another, it may constitute a profound difference.

Although a given variable may not significantly change a numerical result of a mathematical equation, even an insignificant change may greatly affect whether a collision would have occurred. Milliseconds max, make a difference as to whether a collision would occur. Further, in formulas involving multiple variables, there is a cumulative effect of a number of small changes in variables that ultimately could have a profound effect in the final analysis. One small inaccuracy may not make a difference; many inaccuracies

No Cross

There are many, instances when the most brilliant cross-examination consists of "Thank You, Your Honor, but it is not necessary to cross-examine this witness." Trial attorneys must always balance the need for cross-examination against its potential to damage a case.

If a witness is harmless or ineffective during direct, a cross-examination merely creates an opportunity. for that witness to salvage his or her testimony. If an adverse witness has testified favorably to a plainfiff's case, there is the overwhelming temptation to go for the kill, to reiterate that testimony with a brilliant" cross-examination. But in that case, cross merely gives the witness m opportunity to rehabilitate the testimony. Just say "no" to cross-examination.

Also, some witnesses are simply, unimpeachable. They, testify to factual accounts or opinions that cannot be contested. Lawyers should never give the unimpeachable witness the opportunity to hurt their case again during cross.

There are no universal rules for the cross-examination of an accident reconstructionist - or any other witness, for that matter. In all cases, however, the cross-examiner should prepare carefully, employ logical thought, and exercise selfcontrol. By understanding the deficiencies of an adverse witness's analysis, the cross-examiner will help lead the trier of fact to an independent determination that the witness is wrong.

Notes

(1) ACTAR Update, The SOARce, Spring/Summer 1994, at 1. [The SOARce is the official publication of The Society of Accident Reconstructionists.] (2) Daubert v. Merrell Dow Pharmaceuticals, Inc., 113 S. Ct. 2786, 2976 (1993). (3) Logsdon v. Baker, 336 F. Supp. 332, 336 (D.D.C. 1973), vacated 517 F.2d 174 (D.C. Cir. 1975). (4) Id. (5) Head v. Lithonia Corp., Inc., 881 F.2d 941, 943 (10th Cir. 1989); Greenwood Utils. Comm'n v. Mississippi Power Co., 751 F.2d 1484, 1495 (5th Cir. 1985). (6) Logsdon, 366 F. Supp. 332, 338; Gilbert v. Gulf Oil Corp., 175 F.2d 705, 709 (4th Cir. 1949). (7) Ronald L. Carlson, Experts as Hearsay Conduits; Confrontation Abuses in Opinion Testimony, 76 MINN. L. REV. 859 (1992). "Minnesota amended its evidence rules to embrace a policy prohibiting, on direct examination, the wholesale introduction of background documents used by an expert to reach his or her conclusion." Id. at 860. Cf David L. Faigman, Commentary: A Response to Professor Carlson: Struggling to Stop the Flood of Unreliable Expert Testimony, 76 MINN. L. REV. 877 (1992). (8) Lewis v. Rego Co., 757 F.2d 66 (3d Cir. 1985); United States v. Affleck, 776 F.2d 1451 (10th Cir. 1985); Paul R- Rice, Inadmissible Evidence as a Basis for Expert Opinion Testimony: A Response to Professor Carlson, 40 VAND. L. REV. 583 (1987). (9) Department of Corrections v. Williams, 549 So. 2d 1071 (Fla. Dist. Ct. App. 1989). (10) Dudley Sports Co v. Schmitt, 279 N.E.2d 266, 276 (Ind. Ct. App. 1972). 31A AM. JUR. 2D Expert nd Opinion Evidence $345 Observation (citation omitted) (1989). (12) James Stannard Baker, Limitations on Accident Reconstruction, 8 DEF. L.J. 3, 6 (1960). (13) "Yaw" is "a sidewise movement of a vehicle in turning," A "yawmark" is "the mark made on the road by a rotating tire that is slipping in a direction parallel to the axle of the wheel." J. STANNARD BAKER & LYNN B. FRICKE, THE TRAFFIC ACCIDENT INVESTIGATION MANUAL (1986). Therefore, skid marks do not necessarily, represent braking. Understanding whether marks found at an accident scene properly represent a skid or a yaw will determine which mathematical equation is to be applied. (14) James C. Wambold, Limitations of Using Skid Number in Accident Analysis, ACCIDENT RECONST. J., May/June 1992, at 38. (15) Howard Nations, Powerful Persuasion in the Court Room, State Bar of Texas (1993).