Corinne Atton and William Solander explain the role of expert witnesses and how they may often be issue- or case-determinative in US patent litigation.
Expert witnesses are omnipresent in US patent litigation. A key reason for this is the central role and function, in US patent law, of a person of ordinary skill in the art (POSA). Other reasons include the complexity of the science and technology that is litigated, and the fact that while many US judges are experienced in patent cases, they may not have scientific or technological expertise. Expert witnesses may provide the most important evidence of liability and damages at trial and their testimony may be case determinative. Even before trial, an excellent expert, under the careful guidance of attorneys, may help to secure significant successes. A favorable claim construction may be claim or defense determinative, and a compelling expert report may prompt settlement discussions. It is therefore essential that parties identify the elements of their case that may require expert testimony, and retain a full contingent of experts that will support their case as early as possible. Careful selection of experts, careful drafting, and rigorous preparation are key.