Following a long run of Delaware precedent on the admissibility of expert testimony related to patent law, Judge Bartle granted in part plaintiffs’ motion to strike the expert witness report of defendants’ patent law expert. Brigham and Women’s Hospital, Inc. v. Teva Pharmaceuticals USA, Inc., C.A. No. 08-464, Memo. (D. Del. Sept. 21, 2010). Defendant’s expert is a lawyer with a master’s degree in chemistry, and his report includes sections on the “doctrine of inequitable conduct, the duties of disclosure and inquiry in patent prosecutions, obviousness-type double-patenting, and the effect of the TRIPS Agreement and GATT Amendment on patent terms,” opinions that certain information not disclosed to the examiner was material to prosecution and finally, certain various PTO practices and procedures. Judge Bartle stated that “the law of this district is clear that experts in patent cases may no opine on whether a party engaged in inequitable conduct, discuss whether certain information was material to a pending patent application, or otherwise provide legal conclusions on ‘substantive issues of patent law'” and that parties are further prohibited from using experts to “explain patent prosecution histories.” Id. at 3. Therefore, the Court granted plaintiffs’ motion to strike the expert report except for that portion that explains the PTO’s practices and procedures. Id. at 4.