Lightfoot v. MXEnergy Elec., Inc., 690 F.3d 352 (5th Cir. 2012):

Under Federal Rules of Evidence 702 and 703, the trial judge serves as a gatekeeper to ensure the reliability and relevance of expert testimony. The Supreme Court has provided factors to inform the reliability determination, but the inquiry is a "flexible" one, and trial courts have "broad latitude when [deciding] how to determine reliability and in the reliability determination itself. Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137, 141-42, 119 S. Ct. 1167, 1171, 143 L. Ed. 2d 238 (1999). This court has previously noted that "[m]ost of the safeguards provided for in [Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. Ct. 2786, 125 L. Ed. 2d 469 (1993),] are not as essential in a case such as this where a judge sits as the trier of fact in place of a jury." Gibbs v. Gibbs, 210 F.3d 491, 500 (5th Cir. 2000). Whether Daubert's suggested indicia of reliability apply to any given testimony depends on the nature of the issue at hand, the witness's particular expertise, and the subject of the testimony.

Footnote 7. The suggested indicia of reliability in Daubert center around the type of scientific evidence at issue in that case, and its specifically suggested factors neither necessarily nor exclusively apply to all experts or in every case. Carmichael, 526 U.S. at 141, 119 S. Ct. 1167, 1171.

Mayer's testimony established that he had extensive experience in the field of commodity trading and played a key role in drafting frequently used form contracts before becoming the head of MX. His function as an expert was to help the court understand the typical structure of forward contracts within his industry. Mayer was well-versed in the field his testimony described. That he was an interested expert witness, testifying on behalf of MX while also serving as its CEO, goes to the weight, not the admissibility, of his testimony. Rodriguez v. Pacificare of Texas, Inc., 980 F.2d 1014, 1019 (5th Cir. 1993). Further, Mayer's testimony describing the market and contracts with which he was familiar did not rest on scientific principles or theories and therefore did not require scientific substantiation. See Pipitone v. Biomatrix, Inc., 288 F.3d 239, 244 (5th Cir. 2002) (The requisite "analysis is a flexible one, and . . . the factors identified in Daubert may or may not be pertinent in assessing reliability, depending on the nature of the issue, the expert's particular expertise, and the subject of his testimony." (quoting Carmichael, 526 U.S. at 150, 119 S. Ct. 1167, 1175 (internal quotation marks omitted))). We do not find an abuse of discretion in the bankruptcy court's acceptance of Mayer's expert testimony regarding his field.