Abbott Laboratories v. Baxter Pharmaceutical Products, Inc. 2006 WL 3231411 (Fed. Cir. 2006).

The Federal Circuit has held that the lack of knowledge in prior art is irrelevant to the question of whether a patent claims something “new” over the prior art disclosed. In Abbott v. Baxter, the alleged infringer claimed that a prior art mixture of anesthetic sevoflurane saturated with water inherently anticipated a patent on a water-saturated sevoflurane mix, an inhalation anesthetic, even though the fact that it was resistant to acid degradation, a property claimed in the second patent, was unknown at the time of the prior art. Reversing a district court’s ruling of no invalidity, the Federal Circuit held that the prior art inherently anticipated the patent even though the relevant property of the prior art was not appreciated at the time. Specifically addressing the district court’s reliance on Bristol-Myers Squibb v. Ben Venue Labs., Inc., the Federal Circuit noted that the holding in that case that “new uses of known processes may be patentable” applies only to process claims, not to composition claims such as the one at issue.