Under the now widely adopted Daubert standard, courts evaluate expert testimony based on the principles and methodology underlying the expert witness’s opinion. Admissibility of expert testimony is not governed by whether the factual underpinnings of the opinion are sound, or the conclusions correct, but rather by the relevancy and reliability of the methods applied in forming said opinion.The U.S. District Court for the Northern District of Illinois recently illustrated these principles in Johnson v. Orton.How did …