Addressing the distinction between conception and reduction to practice and the requirement for written description in the unpredictable arts, the US Court of Appeals for the Federal Circuit explained that proof of conception of an invention does not require that the inventor appreciated the invention at the time of conception. Knowledge that an invention is successful is only part of the case for reduction to practice. Regents of the Univ. of Cal. et al. v. Broad Inst. et al., Case No. 22-1594 (Fed. Cir. May 12, 2025) (Reyna, Hughes, Cunningham, JJ.)

The Regents of the University of California, the University of Vienna, and Emmanuelle Charpentier (collectively, Regents) and the Broad Institute, Massachusetts Institute of Technology, and the President and Fellows of Harvard College (collectively, Broad) were each separately involved in research concerning CRISPR systems that “are immune defense systems in prokaryotic cells that naturally edit DNA.” At issue was the invention of the use of CRISPR systems to modify the DNA in eukaryotic cells. Regents and Broad filed competing patent applications resulting in an interference proceeding under pre-AIA law at the US Patent & Trademark Office Board of Patent Appeals & Interferences to determine which applicant had priority to the invention.

The main issue before the Board was a priority dispute over who first conceived of the invention and sufficiently reduced it to practice under pre-AIA patent law. Regents submitted three provisional patent applications dated May 2012, October 2012, and January 2013 and moved to be accorded the benefit of the earliest filing date, May 2012, for the purpose of determining priority. Alternatively, Reagents sought to be accorded either October 2012 or January 2013 as its priority date. The Board found that Regents’ first and second provisional applications (filed in May and October 2012, respectively) were not a constructive reduction to practice because neither satisfied the written description requirement of 35 U.S.C. § 112. The third provisional application, filed in January 2013, was the first to amount to a constructive reduction to practice of the counts in interference. The Board then ruled that Broad was the senior party for the purposes of priority in the interference proceeding because Broad reduced the invention to practice by October 5, 2012, when a scientist submitted a manuscript to a journal publisher. The Board ruled that Regents failed to prove conception of the invention prior to Broad’s actual reduction to practice. Regents appealed.

Regents argued that in assessing conception, the Board “legally erred by requiring Regents’ scientist to know that their invention would work.” The Federal Circuit agreed and vacated the Board’s decision. As the Court explained, there are three stages to the inventive process: conception, reasonable diligence, and reduction to practice. At the conception stage, “an inventor need not know that his invention will work for conception to be complete.” Rather, knowledge that the invention will work, “necessarily, can rest only on an actual reduction to practice.” The Board therefore legally erred by requiring Regents to know its invention would work to prove conception.

The Court found that the Board should have considered whether a person of ordinary skill in the art could have reduced the conception to practice using only routine skill or routine techniques “without extensive research or experimentation.”

Evidence of purported experimental success by others (at the time of the conception), and the use of routine methods in subsequent successful experiments are pertinent to the inquiry. Here the Board erred by focusing on the difficulties Regents’ inventors encountered and their doubts of success rather than on “routine methods or skill.” The Federal Circuit noted that a complete conception does not occur if “a research plan requires extensive research before the inventor can have a reasonable expectation that the limitations of the count will actually be met.” That issue should be determined by considering “the reasonable expectation of a person of ordinary skill in the art” and whether that person would “have been able to reasonably predict” that experimentation would produce the claimed result. On remand, the Court instructed the Board to evaluate whether the later party to reduce to practice was the first to conceive of the invention and subsequently exercised reasonable diligence in reducing the invention to practice, or whether it was the first to conceive of the invention that then communicated the conception to the adverse claimant.

Regent also argued that the Board legally erred in its written description analysis by requiring the first provisional application “to convince a person of ordinary skill in the art that the invention will work in eukaryotes.” The Federal Circuit disagreed because the written description requirement mandates that a patent’s disclosure “must clearly recognize that the inventor invented what is claimed.” The test requires a court to “determine how a person of ordinary skill in the art would understand the four corners of the specification.” The Board correctly analyzed whether a person of ordinary skill in the art would understand that Regents had possession of the claimed subject matter considering the “highly unpredictable and complex” subject matter.