Carl F. Thelin

OPINION AND JUDGEMENT

Is there a difference between an opinion and a judgment?

Cher may have an opinion about the bene­fits of a brand of coffee sweetener, but I would rather trust the judgment of a chem­ist as to what it really does.

A layperson can express an opinion about anything, but he can't testify in court as an expert on automo­bile reconstruction and crashworthiness.

The complexity of the case may go beyond the need for a reconstruction of the dynamics of an automo­bile collision if the issue is personal injury causation. Perhaps you have a case alleging that a defective product caused an injury or made it worse. Then you need a team of experienced specialists working to­gether. Here are examples of opinions requiring dif­ferent levels of an expert's professional judgment:

A) "It is my opinion, within a reasonable degree of engineering certainty, that, having measured the length of the skid marks from vehicle 'A', and having estimated the coeffi­cient of friction and the perception - res­ponse time of the driver, that vehicle 'A' was 187 feet from the point of the collision and moving at 47 mph when the driver first be­came aware of the threat of a collision."

B) "It is my opinion, within a reasonable degree of engineering certainty, that, had the driver of vehicle "A" been using the available lap and shoulder belt, his injuries in this col­lision would not have been serious or fatal"

C) "It is my opinion, within a reasonable degree of engineering certainty, that the driver's seat in vehicle 'A' was defectively designed, in that it moved forward during the collision with sufficient force as to render the driver's injuries much worse than they would have been had the seat remained in place."

Each of the above statements represents varying de­grees of technical judgment based on a combination of measured objective values and subjective assess­ments. To judge something "not acceptable" is a serious matter, and it is important to understand what the expert relies on to form his opinion.

Statement 'A' requires skill in measuring such things as the length and curvature of tire skid marks. The Reconstructionist uses judgment in estimating ap­propriate values for vehicle crush characteristics and collision angles that are not directly measurable.  The resulting conclusion is derived by entering those numbers into formulas that are derived from the laws of physics. These formulas have been proven through experience and testing to provide reasonable simula­tions. The quality of the conclusion is re­flected in the realism of the assumptions and on which formu­las are applicable. That quality comes from the ex­pert's experience and judgment from examining many similar events.

Statement 'B' involves several expert opinions. The first is to determine the severity of the collision of the vehicle (statement 'A'). Another assessment is made as to the severity of the injuries to the driver. Finally someone must make a judgment as to whether the use of the seatbelt would have made a significantly large difference in the injuries. Now the judgment concerns the motions of the driver, and the effect of his collisions with the interior of the vehicle. There are computer programs that model the motions of the occupants during a crash. The assess­ment of the injuries and the effectiveness of the restraint system require professional judgment because there are a number of factors that cannot be directly measured.

Statement 'C' involves additional expert opinions. Besides those above, now the judgment call is this: was there another seat system that would have made it reasonably probable that the injury would not have been significantly serious? This expert cannot just imagine that there is some sort of "ideal" non-defec­tive product that would have made the difference. He must have the experience to know that there is at least one. It is not enough to just invent a solution. Hindsight is always perfect. It is more appropriate to show that there was already a competitive, tested product that did provide the necessary safe perfor­mance. The product does not necessarily have to be on the market, but it is important to show that its feasibility was public knowledge. If anyone else could do it right, this maker has no excuse for not doing it right. 

Similar judgments may be required even when a possible product defect is not an issue. Sometimes the issue may be, "Was the injury due to collision severity that exceeds crashworthiness of any reason­able vehicle?", or “Was the injury worsened by failure to use the available seatbelts properly?"