No matter whether you are the patent owner or petitioner in an IPR, expert witness testimony is an important aspect of building your case. The Board relies on expert witnesses to provide insight into the often highly technical aspects of a given case, and will inevitably choose to give more weight to the testimony of one side’s witness over the other. This can be especially true when the testimony of the opposing experts is in direct conflict. So how does the Board choose which expert testimony to give more weight? Sometimes it’s a question of timing, as in the recent decision in Mylan Pharmaceuticals Inc. v. AstraZeneca (IPR2015-01340).
In this case, the petitioner and patent owner presented conflicting expert witness testimony describing how a person of ordinary skill in the art at the time the application was filed would have chosen a “lead compound” for further development. The Board held that the petitioner failed to establish the challenged claims were unpatentable on obviousness grounds, largely on the basis that a person of ordinary skill in the art would not have selected the lead compound suggested by the petitioner’s expert in view of the testimony of the patent owner’s expert.
In making that determination, the Board stated that the patent owner’s expert was more credible because “she ‘faced the problem the person of ordinary skill in the art would,’ ‘did it the way a person skilled in the art would,’ and ‘went through the lead compound analysis’ at the time of the invention.” On the other hand, the experience of the petitioner’s expert was limited to working with the co-inventors of the patent at issue after the invention of the claimed compound had been made. Thus, the Board concluded that the patent owner’s expert better represented the way a person of ordinary skill in the art would have faced the problem of selecting a lead compound because that expert entered the relevant field “at the relevant time, i.e., the time of invention.” The petitioner’s expert, on the other hand, entered the field after the alleged lead compound would have been selected.
Whether viewed from the perspective of the patent owner or petitioner, this decision illustrates that in cases where the thought process of a person of ordinary skill in the art is likely to be disputed, such as in the context of a “lead compound analysis,” selecting an expert witness having the right experience at the relevant time can influence the Board to give more weight to that expert’s testimony and ultimately win the day.