Patently Non-Obvious: Empirical Demonstration that the Hindsight Bias Renders Patent Decisions Irrational

73 Pages Posted: 28 Dec 2005 Last revised: 26 May 2016

See all articles by Gregory N. Mandel

Gregory N. Mandel

Temple University - James E. Beasley School of Law


This Article reports an experimental study that provides the first empirical demonstration of the hindsight bias in patent law. The results are dramatic along several fronts: (1) the hindsight bias distorts patent decisions far more than anticipated, and to a greater extent than other legal judgments; (2) jury instructions that explicitly identify and warn against the hindsight bias do not ameliorate its impact; (3) the admission of secondary consideration evidence does not cure the hindsight bias; (4) neither the Federal Circuit's suggestion test nor the Supreme Court's Graham requirements appear to solve the hindsight problem; and (5) the hindsight problem pervades patent law to an extent not previously recognized - it biases decisions under the doctrine of equivalents, claim construction, the on-sale bar, and enablement.

These findings run counter to the dominant patent analysis of the last decade and have significant implications for patent and innovation policy. The study results indicate that the non-obvious requirement actually often may be applied too stringently. Numerous critics of the current non-obvious requirement may need to reconsider the bases of their challenges and revisit their prescriptions for reform. Revising non-obvious doctrine or practice, for instance, will not provide the panacea that most assume. This Article concludes with recommendations for changes in patent doctrine and litigation to mitigate the impact of the hindsight bias.

Keywords: hindsight, nonobvious, non-obvious, bias, patent, debias, invent, innovate, jury, secondary consideration, suggestion, KSR, Teleflex

JEL Classification: K30, K40, K41

Suggested Citation

Mandel, Gregory, Patently Non-Obvious: Empirical Demonstration that the Hindsight Bias Renders Patent Decisions Irrational. Ohio State Law Journal, Vol. 67, p. 1391, 2006, 1st Annual Conference on Empirical Legal Studies Paper, Available at SSRN: or

Gregory Mandel (Contact Author)

Temple University - James E. Beasley School of Law ( email )

1719 N. Broad Street
Philadelphia, PA 19122
United States
(215) 204-2381 (Phone)

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