Pertile, a front seat passenger, was badly injured in a rollover. GM’s expert, Ms. Lu, issued a report which states that the roof structure was evaluated in tests that subjected the design to various collision speeds, impact directions and loading directions, and opined, in part based upon her “review of the technical reports and engineering documents” that the 2011 Chevrolet Silverado 2500HD crew cab pickup truck met and exceeded the applicable FMVSS requirements, that the roof structure exceeded the strength-to-weight ratio requirement, and that the processes and evaluations that GM undertook in designing and assembly of the GMT900 pickup trucks were reasonable and appropriate. Both Ms. Lu and the plaintiff’s expert made use, in different ways, of Finite Element Modeling (FEM) or Finite Element Analysis (FEA) engineering techniques. FEA, in particular, refers to “a computer modeling technology used to create a mathematical simulation of three dimensional, virtual representation of a vehicle, component or system subjected to prescribed load conditions.”  The defendant’s expert, Ms. Lu, has stated that: “GM uses computer modeling technology to create a mathematical simulation of a three dimensional, virtual representation of a vehicle, system or component that is subjected to prescribed load conditions. These simulations attempt to predict aspects of the behavior of a system by creating and running an approximate, mathematical model of it.”

Earlier in the litigation, Plaintiffs sought to compel production of GM’s FEA modeling of the 2011 model Chevrolet Silverado 2500 HD crew cab pickup. Magistrate Judge Wang found, even accepting that the FEA Models were relevant, that Plaintiffs had nevertheless not established that they were necessary, in part because of the other computer design materials that GM had furnished to Plaintiffs, and in part because she relied on GM’s representations that the FEA models in its possession did not reflect the final design of the vehicle at issue.  In subsequent discovery disputes, the magistrate judge compelled the plaintiff’s expert, Dr. Vlahinos, to provide GM with the electronic inputs and outputs associated with his FEA Model, and also authorized Plaintiffs to file a formal motion related to the FEM model data if they could establish that Defendants’ experts relied upon GM’s FEM data that was previously withheld.

Plaintiffs subsequently filed a motion to compel, arguing that the deposition testimony of Ms. Lu and another GM employee had revealed that GM was, in fact, in possession of three FEMs reflecting the final production level design of the truck in which Mr. Pertile was injured, and that Ms. Lu had considered GM’s FEM data in forming her opinions.  GM objected, arguing that its expert “neither used nor relied on” GM’s FEM models, and that “to the extent she offered any testimony about the strength of the vehicle’s roof, it was based on the report of the analysis done in development of the vehicle (the model for which no longer exists), and on a physical test conducted that confirms the strength of the roof design,” but not on the underlying FEA modeling itself.  The magistrate judge compelled production, and the district court affirmed.

With respect to the question of whether GM’s expert “considered” the FEM data under Rule 26, the court did not think that “Ms. Lu’s affidavit should be taken as conclusive by itself on the question of what she ‘considered.’ The Court sees little reason to credit Plaintiffs’ argumentative attack on Ms. Lu’s honesty…. Still, and quite significantly for our purposes here, the parties have inherently asymmetrical access to information regarding what materials Ms. Lu has reviewed or considered that might relate in some way to her opinions, especially considering her long tenure working at GM. More importantly, however, GM cites no contrary authority showing Judge Wang erred in holding that the word ‘considered’ … ‘means something broader than “relied upon,” but something less than material simply in the background knowledge of the expert,’ and that a proper application of Rule 26(a)(2) must ‘provide an adversary with sufficient information to engage in meaningful cross-examination’ of an opposing expert.”

The district court also found no clear error in the magistrate’s ruling rejecting GM’s proposed protocol for an onerously restrictive on-site inspection of the FEA Model. “GM’s counter-arguments establish that GM is highly protective of these data, that it treats them as highly confidential, and that it would strongly prefer to proceed under its own restricted inspection protocol” and “should be permitted to encrypt the ‘Material cards’ and ‘Control Parameter cards’ of its model, arguing that these highly confidential portions of the FEA Model ‘relate to the question of the “How” a particular type of material is modeled,’ rather than ‘”What” is being modeled.’ Given this description, the Court rejects GM’s argument that these aspects of its FEA Model are not relevant to the purposes of production under Rule 26(a)(2)(B). To the contrary, understanding ‘How,’ GM’s modeling works, in addition to ‘What’ it models is highly relevant to the main purposes of this production, including allowing Dr. Vlahinos to determine ‘how’ GM’s Models either are or are not superior to his own.”


Pertile v. General Motors, No.15-0518, 2017 WL 3767780 (D.Colo. Aug. 31, 2017).