Document Type


Publication Date

Summer 2011

Publication Citation

86 Indiana Law Journal 779 (2011)


Patents are peculiar legal instruments in that they contain both technical and legal information. This Janus-like nature of the documents is important because they serve the legal purpose of affording the owner the right to exclude others from practicing the invention, and third parties need to be able to assess the scope of that right. At the same time, through the patent’s disclosure, the document is intended to contribute to the storehouse of technical knowledge. Superficially, patents are generally viewed through the eyes of the hypothetical person having ordinary skill in the art (PHOSITA), patent law’s “reasonable person.” Unfortunately, the U.S. Court of Appeals for the Federal Circuit has marginalized the PHOSITA by treating the document, particularly in claim construction and in assessing the sufficiency of the patent’s disclosure, as a purely legal document. While this shift is understandable, it is also unfortunate. Possible justifications for the court’s move are unpersuasive. For instance, from the ex ante perspective, the court may hope to encourage future applicants to provide better disclosures. As this Article explains, that argument fails because the court’s legal standards are too vague and the lapse of time between the application and a competitor’s review of the patent causes informational asymmetries for which the applicant cannot account. From an ex post perspective, this shift may assist lay judges and juries in evaluating patents, but such a result is the problem—this treatment reduces the technical value of the patent and incentivizes future applicants to treat the disclosure in a legal fashion, not as a technical resource.

To balance the interest in public notice with the technical nature of the patent, this Article posits the use of presumptions. Courts should use the intrinsic evidence—the patent and the prosecution history—to generate a presumptive conclusion as to the construction of the patent or the sufficiency of the patent’s disclosure. Then, the court should resort to the extrinsic evidence to determine whether the legalistic conclusion reached should be rejected in light of the understanding of technologists in the relevant field. In this way, the default position for courts is interpretation afforded by the intrinsic record, enhancing public notice. This default, however, can be rebutted when facts regarding the technical import of the document are brought to bear, bringing the viewpoint of the PHOSITA into the calculus.