Mass. State Police “Critical Speed Formula” Excluded in Daubert Hearing

Commonwealth vs. Cruz (Norfolk Superior Court Criminal Action No.: 10-0508)
December 30, 2011

The following is a summary of the recent decision of Commonwealth vs. Cruz. Hassett & Donnelly was not involved in the handling of this case. The decision appears to be noteworthy for attorneys and claims adjusters involved in handling serious or fatal motor vehicle accident claims requiring the use of accident reconstruction experts.

In Commonwealth vs. Cruz, Norfolk Superior Court Criminal Action No.: 10-0508 (December 30, 2011), Kenneth Fishman ruled to exclude the testimony of Massachusetts State Troopers relative to the methodology used to determine the speed of a motor vehicle involved in a fatal motor vehicle accident.

Following a 2010 motor vehicle accident, defendant operator, Elvis Cruz, was indicted for manslaughter and two counts of operating under the influence of alcohol following the death of his passenger, Joel Martinez. Mr. Cruz was driving on Route 95 in Norwood when his vehicle struck the left guardrail, crossed the center and right lanes of travel, crashed through the right guardrail and rolled over multiple times down an embankment before finally coming to rest. During the accident, passenger Martinez was ejected from the vehicle and suffered fatal injuries.

The Massachusetts State Police Collision Analysis Reconstruction Section used a drag sled and the “critical speed formula” to opine that the defendant had been traveling 99 miles per hour at the time of the accident. Defense counsel filed a Motion to Exclude the State Police accident reconstruction opinion testimony, questioning the validity of the speed estimates and the techniques used by State Police. Further, the defense argued that the methodology used by police was not reliable and/or was not properly applied in the accident reconstruction.

According to scientific literature published by the Institute of Police Technology and Management and submitted into evidence at the hearing, two opposing forces, centripetal and centrifugal force, come into play when a vehicle enters a curve. Centripetal force strives to keep the vehicle moving in its current curved path while centrifugal force strives to allow the vehicle to veer from the curved path. When a vehicle turns at excessive speed, the centrifugal force become greater than the centripetal force and the rear of the vehicle “sideslips” or moves out from the curved path in which it had been moving. This sideways movement is called “yaw” and the speed at which it occurs is called the “critical speed.” The critical speed yaw leaves characteristic tire marks on the roadway. Calculation of the radius of the yaw marks starts from the point where the rear tire mark crosses over the front tire mark. In short, two tire marks must be present for the calculation to be accurate, according to the literature presented. Here, the State Police accident site photos were taken in the dark and did not reveal any yaw marks in the roadway. Further, the diagram produced by the investigating trooper indicated only one tire mark and did not depict any crossover marks.

During the Daubert hearing, the defense offered the testimony of Richard Montefusco, engineer and certified accident reconstruction expert. Montefusco opined that drag sleds are generally unreliable when used for accident reconstruction and that the investigating trooper’s critical speed formula was flawed. Using alternate formulas and methodology, Montefusco opined that the speed of the vehicle was actually 64 miles per hour when it left the roadway.

In his opinion, Judge Fishman emphasized that the existing literature expressly states that a collision itself does not produce a critical speed yaw in roadway and post-collision trajectory should not be used to determine critical speed. Further, Judge Fishman noted a dispute as to whether the one tire mark was caused during the vehicle’s collision with the guardrail or just before the collision with the guardrail, thus creating a question as to whether critical speed formula would apply in this instance. However, Judge Fishman concluded that the question regarding the timing of the yaw mark would be a question for the jury and would not compel the exclusion of the trooper’s testimony.

The defense expert, Montefusco, testified that many human factors can affect the results of drag sled testing and, as such, drag sleds are not reliable for use in accident reconstruction. Judge Fishman made note of Montefusco’s testimony, but stated that same would likely go to the weight of the trooper’s testimony and not to the admissibility thereof. At the hearing, one trooper with significant experience in collision analysis acknowledged that the accuracy of the drag sled procedure is dependent upon an officer’s technique and that, when possible, skid tests or accelerometers are preferable for use in accident reconstruction.

Finally, Judge Fishman opined that based on the literature submitted into evidence at the hearing, the critical speed formula cannot be used to provide a speed estimate when only one tire mark exists. Without two tire marks showing a point of intersection, the measurements would be inconsistent with the methodology needed for the critical speed formula. Therefore, the Judge ruled that the trooper’s opinion is based on an “insufficient evidentiary foundation” and should be excluded.

This decision not only highlights the possible weaknesses in the accident reconstruction techniques currently employed by State Police and other accident reconstructionists, but it also underscores the need to retain qualified and experienced accident reconstruction experts when handling catastrophic and fatal motor vehicle accident claims through trial.

For further information about the implications of this decision, please feel free to contact Attorney David Hassett at (508) 791-6287 at any time.