Hal Wegner has analyzed the current status of case law regarding chemical compound obviousness, and holds that "KSR and Pfizer v. Apotex manifest fundamental misunderstandings of chemical practice case law."
Selective excerpts from the summary of this exceptional research and analysis:
The law of obviousness of a chemical compound evolved from late nineteenth century structural obviousness case law that became highly defined in the 1940’s and was modified in the early 1960’s to provide a balanced two part analysis: The Examiner has the initial burden to establish prima facie or “structural” obviousness, but where this is established, it is up to the patent applicant to present rebuttal evidence demonstrating actual differences between the claimed compound and the prior art.
Over a period of decades, literally thousands of cases, largely at the Board of the U.S. Patent and Trademark Office (PTO), have established an intricate doctrine of “structural” obviousness. An equally intricate body of CCPA case law starting in the early 1960’s created a framework for demonstrating the nonobviousness of the invention as a whole by proving actual differences in properties over the prior art. Shortly after Papesch, the court focused upon whether a compound which is “obvious to try” – and hence prima facie obvious – could nevertheless be demonstrated to be as nonobvious as a whole through a Papesch-based showing of unexpected differences.