In SmithKline v. Apotex, the Court of Appeals for the Federal Circuit invalidated the main patent on Paxil as inherently anticipated. In doing so, the court over-stepped the bounds of appellate review, and broadened the scope of the inherent anticipation doctrine to include chemical structures that are not measurably produced by strict practice of the prior art. This holding does not comport with well-settled precedent and could have dire consequences for the patentability of many chemical structures. A more equitable invalidity analysis would require a chemical structure to derive directly from a disclosed reaction in order to be anticipated; in all other cases, the chemical structure must be proven obvious.
Bryan William Jones, Smithkline v. Apotex: Broadening The Scope Of Inherent Anticipation And Its Impact On The Patentability Of Chemical Structures, 5 J. Marshall Rev. Intell. Prop. L. 456 (2006)