Timing Matters: Prior Art’s Age Infers Patent Nonobviousness

32 Pages Posted: 4 Mar 2015 Last revised: 10 Jul 2022

See all articles by J.L. Tran

J.L. Tran

affiliation not provided to SSRN

Date Written: April 30, 2014


Many assume that prior arts do not depreciate, and thus, last forever. However, the public knowledge expands rapidly over time. Thus, this assumption can potentially slow innovation rate, because without capping how long prior arts last in analyzing patent nonobviousness, ideas for new inventions can eventually run out. Until now, no one has challenged this assumption nor questioned whether a prior art depreciates and/or how long a prior art lasts. Recently, the United States Court of Appeals for the Federal Circuit shed some light into these questions: Leo Pharmaceutical Products, Ltd. v. Rea found that “the elapsed time between the prior art and [Leo’s] patent's filing date evinces that [Leo’s] invention was not obvious to try.”

Nonobviousness is the most difficult requirement for a patent applicant, and the most frequent ground upon which courts invalidate a patent. Courts to date have developed nine non-technical secondary considerations to help fact-finders infer nonobviousness. This paper proposes a tenth secondary consideration: prior art’s age. Building on the Leo decision, this paper aims to dispel the myth of measuring a prior art’s value and age in the patent nonobviousness context. This paper suggests that old prior arts depreciate over time in evaluating a patent’s nonobviousness. Specifically, a prior art starts depreciating after about 10 years from the date of adding such prior art to the “storehouse of knowledge.” This paper then shows how to measure and use prior art’s age to infer nonobviousness, applies it to the recent cases and to industries, discusses why using it makes sense, and addresses the possible counterarguments to using it.

Prior art’s age directly follows current precedents, and stems from another highly persuasive secondary consideration, long-felt need. It helps fact-finders infer nonobviousness quickly and easily, while still encourages innovation. It will likely not lead to an increased rate of finding patents valid, but actually an increased rate of courts correctly upholding truly nonobvious patents.

Keywords: patent, obviousness, non-obviousness, 103

Suggested Citation

Tran, Jasper, Timing Matters: Prior Art’s Age Infers Patent Nonobviousness (April 30, 2014). Gonzaga Law Review, Vol. 50, p. 189, 2014-15 symposium, Available at SSRN: https://ssrn.com/abstract=2562948

Jasper Tran (Contact Author)

affiliation not provided to SSRN

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