Not all experts know things in exactly the same way

"...In the summer of 1999, the United States Supreme Court issued the last in a trilogy of 1990s cases dealing with the question of the admissibility of expert testimony in federal courts. In Kumho Tire Co. v. Carmichael, the Court was asked to decide if the judicial gatekeeping role it set forth in the first of these three cases, Daubert v. Merrell Dow Pharmaceuticals, applied only to "scientific" knowledge or to all expert testimony. The court concluded that all expert testimony must be both relevant and reliable before it can be admitted, but that the specific factors set forth in Daubert to judge the reliability of scientific evidence may be supplemented and perhaps replaced by other factors when expert testimony is based on "technical" or "other specialized" knowledge. The opinion explicitly recognized that not all expert testimony can be judged by a single standard because not all experts know things in exactly the same way ..." - From Kumho and how we know by Joseph Sanders.

Enjoy.