In addition to regular examination, the asserted patents had also been reexamined by examiners at the PTO. Later, during litigation, several already cited references were used by courts as invalidation tools.
Patents are given a presumption of validity. When previously considered references are asserted in an invalidity defense, the presumption of validity is even stronger. Courts reason that such a challenge “bears the added burden of overcoming the deference that is due to a qualified government agency presumed to have done its job.”
Here, however, the CAFC gave little weight to the Examiner’s review of references after finding a misstatement in the Examiner’s reasons for allowance.
The examiner … summarized her analysis of the prior art by stating that none of the cited references “addresses the presence of hematopoietic stem cells in umbilical cord or placental blood, that these cells may successfully be cryopreserved, or that, as a collection from a single human at birth, these cells may comprise an amount that is sufficient to effect hematopoietic reconstitution of a human adult.” That explanation is flawed for three reasons. First, as we have explained, the prior art references and the admissions in the specification address the presence of hematopoietic stem cells in cord blood, even though the references may not conclusively prove their presence. Second, Koike established that cord blood could be cryopreserved without substantial losses in the population of progenitor cells; the inventors contributed nothing more with respect to cryopreservation, as their mouse experiments were not performed with cryopreserved blood. Third, while the joint specification states that the amount of cord blood obtained at the time of birth would often be sufficient to transplant an adult, the inventors reached that conclusion simply by comparing the known properties of bone marrow against the results of routine testing of their own cord blood samples.
Although left ambiguous, it appears that the flaws in the Examiner’s final analysis gave the courts reason to take an entirely fresh look at the references in question.