Background
Carol Klopfenstein and John Brent applied for a patent on methods of preparing foods using double-extruded soy cotyledon fiber — a food ingredient they had found could lower cholesterol levels when incorporated into food products. Before filing their patent application, they had presented their research findings at two professional conferences. The first presentation was at a meeting of the American Association of Cereal Chemists (AACC) in October 1998, where their 14-slide presentation was displayed on poster boards for approximately two and a half days. A shorter version was also displayed at a Kansas State University event for less than one day. The slides were printed and mounted for public viewing; no copies were distributed, and the presentation was never catalogued in any library or database.
The Patent and Trademark Office rejected the application, finding that the slide presentation (the “Liu reference,” based on the presenter’s name) constituted a printed publication under 35 U.S.C. § 102(b) that anticipated the claimed invention. The applicants argued that the presentation was not a “printed publication” because it was never distributed, never indexed in any accessible database, and displayed only briefly. The Board of Patent Appeals and Interferences affirmed the rejection, and Klopfenstein and Brent appealed to the Federal Circuit.
The Court’s Holding
The Federal Circuit affirmed the rejection in an opinion by Judge Prost. The court articulated the governing rule for what qualifies as a “printed publication” under § 102(b): the touchstone is whether the reference was sufficiently accessible to the public interested in the art before the critical date. Public accessibility is determined by examining all relevant circumstances — not by applying a rigid checklist of requirements like formal distribution or library cataloguing.
The court identified several factors relevant to the public accessibility inquiry: (1) the length of time the reference was displayed or available; (2) the expertise of the target audience; (3) whether copying or note-taking restrictions were imposed; and (4) the ease with which the subject matter could be copied or reproduced. Applying these factors, the court concluded that the slide presentation was a printed publication. It was displayed for multiple days at a professional conference attended by persons skilled in cereal chemistry who could readily understand and reproduce the disclosed content. No restrictions on copying or note-taking were imposed, and the straightforward bullet-point format of the slides was easily reproducible by an attentive audience member.
The court rejected the argument that formal distribution, indexing, or cataloguing was required. These are factors that can enhance accessibility, but their absence does not automatically disqualify a reference. What matters is whether the relevant technical community had meaningful access to the information — and a multi-day public display at a specialized professional conference, with no copying restrictions, provided exactly that kind of access.
Key Takeaways
- The legal standard for “printed publication” under § 102(b) is public accessibility — whether the reference was sufficiently accessible to the relevant technical audience before the patent’s critical date, not whether it was formally distributed or catalogued.
- Courts assess public accessibility by examining all relevant circumstances, including: how long the reference was displayed, how expert the audience was, whether there were copying restrictions, and how easily the content could be reproduced.
- A poster or slide presentation displayed at a professional conference without restrictions on copying qualifies as a prior art printed publication even if no copies were distributed and the material was never indexed in any library or database.
- For inventors and their counsel, conference presentations and poster displays can create § 102(b) prior art — both against the inventor’s own filing (if disclosed more than one year before filing) and as prior art against later applications by others.
- The one-year grace period under pre-AIA § 102(b) — or the limited exceptions under post-AIA § 102(b) — provides some protection for inventors who disclose their own work publicly before filing, but inventors should file promptly after any public disclosure to avoid creating prior art against themselves or others.
Why It Matters
In re Klopfenstein is the leading Federal Circuit case on whether informal conference presentations constitute printed publications for patent prior art purposes. The case clarifies that the “printed publication” category in § 102 is broad and functional — it captures any disclosure that meaningfully reaches the relevant technical community, regardless of the physical form or distribution method. Patent law does not require a prior art reference to be formally published, distributed, or catalogued to defeat novelty.
The case has significant implications for researchers in academic and industrial settings who present work at conferences before filing patent applications. A poster displayed at a scientific meeting for even a few days can start the one-year clock under pre-AIA § 102(b) — or, for post-AIA applications, can constitute prior art depending on the circumstances. Inventors should treat conference presentations and poster sessions as potential patent-defeating disclosures and coordinate with patent counsel before presenting research that has not yet been filed. The case also illustrates that the digital age has not fundamentally changed the public accessibility analysis — what mattered in Klopfenstein was the expert audience’s ability to access and copy the information, not the physical format of the display.