Patents

In re Klopfenstein: When a Conference Poster Becomes a 'Printed Publication'

The Federal Circuit held that a slide poster displayed at a scientific meeting can be prior art under §102(b) even though it was never distributed or indexed in any library.

September 15, 2025
A researcher standing beside a poster display at a scientific conference
A fourteen-slide poster shown for two and a half days at a cereal-chemists' meeting sank the patent application. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

In re Klopfenstein, 380 F.3d 1345, No. 03-1583 (Fed. Cir. Aug. 18, 2004), answered a deceptively simple question with lasting consequences for academics and product developers alike: can a poster, displayed at a professional meeting but never handed out or catalogued, be a “printed publication” that bars a patent? Writing for the panel, Judge Prost held that it can. Neither distribution of copies nor indexing in a library is a prerequisite. The touchstone is “public accessibility,” and a temporary display can satisfy it when the surrounding circumstances gave the interested public a meaningful opportunity to capture the disclosed information.

At a glance

  • Case: In re Klopfenstein, 380 F.3d 1345, No. 03-1583 (Fed. Cir. Aug. 18, 2004)
  • Author: Judge Prost
  • Below: Affirming the Patent and Trademark Office’s Board of Patent Appeals and Interferences, which upheld the examiner’s rejection
  • Application: Serial No. 09/699,950, directed to methods of preparing foods from extruded soy cotyledon fiber to lower cholesterol (filed October 30, 2000)
  • Statute: Pre-AIA printed-publication bar, 35 U.S.C. § 102(b)
  • Holding: A displayed poster can be a “printed publication” without distribution or indexing; public accessibility is the governing standard, evaluated through a multi-factor inquiry
  • Disposition: Affirmed; claims unpatentable

The facts: a poster, then a patent application

In October 1998, the applicants — Carol Klopfenstein and John Brent, with colleague M. Liu — presented their research at a meeting of the American Association of Cereal Chemists (AACC), and later at Kansas State University. The presentation took the form of fourteen printed slides pasted onto poster boards. It was titled “Enhancement of Cholesterol-Lowering Activity of Dietary Fibers By Extrusion Processing,” and it disclosed the very subject matter the applicants would later try to claim: that extruding certain dietary fibers produced enhanced cholesterol-lowering activity. The poster was displayed continuously for about two and a half days. No one was told to refrain from taking notes or photographs, and nothing restricted attendees from copying what they saw.

The applicants filed their patent application on October 30, 2000 — more than one year after the AACC display. The examiner rejected the claims under § 102(b), treating the poster (the “Liu reference”) as an invalidating printed publication. The Board affirmed, and the applicants appealed to the Federal Circuit, arguing that a poster that was never distributed in copies and never indexed in any catalogue or database could not qualify as a printed publication.

The doctrinal problem: “printed publication” beyond paper

The phrase “printed publication” predates modern reproduction and information technology, and courts had long since stopped reading “printed” literally. The controlling concept, developed in cases such as In re Hall and In re Cronyn, is “public accessibility”: a reference is a printed publication if it was made sufficiently accessible to the interested public, exercising reasonable diligence, before the critical date. In many prior cases, accessibility was shown through either distribution (handing out or mailing copies) or indexing (cataloguing a thesis or document so a researcher could find it). The applicants in Klopfenstein seized on that pattern, urging that distribution or indexing was a necessary condition.

The Federal Circuit disagreed. Judge Prost explained that distribution and indexing are not elements of the test but merely common ways of proving the underlying question of accessibility. A reference temporarily displayed, even if never distributed and never indexed, can still be publicly accessible. The proper inquiry asks whether, given all the facts, the disclosure was sufficiently available that a person of ordinary skill, exercising reasonable diligence, could have accessed and retained its teaching. The court thus refused to let the absence of the two familiar proxies decide the case.

The multi-factor accessibility test

To structure the inquiry for temporary displays, the court identified several factors to weigh together:

  1. The length of time the display was exhibited. A presentation shown for a sustained period — here, about two and a half days — gives the audience ample opportunity to view, study, and absorb the material. A fleeting glimpse during a brief talk would weigh the other way.

  2. The expertise of the target audience. The AACC meeting drew people of ordinary skill in the relevant art. A knowledgeable audience can understand and retain a technical disclosure from a poster in a way a lay audience could not, increasing effective accessibility.

  3. The existence (or absence) of any reasonable expectation that the material would not be copied. Here there were no restrictions, no confidentiality notices, and nothing forbidding note-taking or photography. The absence of protective measures cut against the applicants.

  4. The simplicity or ease with which the material could have been copied. The poster’s content was presented in concise bullet points conveying a relatively simple concept, so an attendee could readily transcribe or photograph the key teaching. Material that is dense or voluminous and hard to copy in the time available would weigh differently.

Applying these factors, the court concluded that the poster was a printed publication. It was displayed long enough, to a skilled audience, without any restriction on copying, and in a form easy to capture. The § 102(b) bar therefore applied, and the claims were unpatentable.

Open questions

Klopfenstein is a fact-driven framework, and its factors do not resolve every scenario. How short a display, before a sufficiently expert audience, is too short to confer accessibility? Would an express “no photographs” policy or a confidentiality legend have flipped the result, and if so, how strictly must such a restriction be enforced? The court suggested that a reasonable expectation against copying matters, but did not define how that expectation is created or rebutted. The factors also predate ubiquitous smartphone cameras and instant social sharing, which arguably make almost any displayed material trivially copyable; a modern court might find accessibility even more readily. Finally, the analysis assumes a physical display — how the same principles map onto ephemeral conference slides, webinars, or transiently posted online materials remains a developing area.

Implications

  • A poster can be prior art. Displaying a slide poster at a meeting, without handing out copies or indexing it anywhere, can still create an invalidating disclosure. Treat conference displays as potential publications.
  • File before you present. The safest course is to have a priority application on file before any public display of the invention’s teaching. Do not rely on the absence of distribution or indexing.
  • Control the room if you must present early. Restrictions on copying — enforced confidentiality, no-photography rules, limited and credentialed audiences — can weigh against accessibility, but they are not a guaranteed cure and must be real.
  • Audit your researchers’ conference history. Validity and diligence reviews should ask not just about journal articles and patents, but about posters, slide decks, and trade-show displays that may predate filing by more than a year.
  • The principle informs post-AIA practice. Although decided under pre-AIA § 102(b), Klopfenstein’s public-accessibility framework continues to guide what counts as a printed publication.

Frequently asked questions

Does a reference have to be distributed or indexed to be a printed publication? No. Klopfenstein’s central holding is that neither distribution of copies nor indexing in a library is required. Those are common ways of proving public accessibility, but accessibility can be shown by other circumstances, such as a sustained display before a skilled audience free to copy it.

Would a confidentiality notice or “no photos” rule have changed the outcome? Possibly. The court weighed the absence of any reasonable expectation against copying as a factor favoring accessibility. A genuine, enforced restriction on copying could cut the other way, but the court did not hold that any single factor is dispositive, and the restriction would need to be credible.

How does this interact with the one-year grace period? Under pre-AIA § 102(b), a printed publication more than one year before the filing date is an absolute bar. The applicants displayed the poster in October 1998 and filed in October 2000 — outside the one-year window — so the disclosure was disqualifying.

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