At Proofbox, legal certainty and global enforceability are not afterthoughts, they are at the core of what we offer. To further validate our publishing process, we commissioned a comprehensive legal analysis by a European Patent Attorney. The goal: to assess whether a technical disclosure published via Proofbox qualifies as prior art before courts and patent offices across Europe and the United States.
The analysis focused on whether defensive publications made through Proofbox meet the formal and practical requirements to be accepted as valid prior art, including before the EPO, the Unified Patent Court (UPC), and the USPTO.
We are proud to share this in-depth statement below.
Legal Opinion on Proofbox Disclosures
The legal evaluation of online publications with respect to their suitability as prior art under the European Patent Convention (EPC) and U.S. patent law requires a nuanced analysis of the underlying technical and legal conditions. In the present case, the analysis concerns a specific form of online publication provided by the platform Proofbox. Proofbox enables users to upload a technical document into a publicly accessible, web-based archive in exchange for a fee. Each document is timestamped, content-hashed, published in a SEO-optimized blog format with a unique URL, and monitored for permanent availability via daily retrieval logs. In addition, the archive can be filtered by publication date, enabling a systematic and chronological traceability of priority-relevant information. Furthermore, Proofbox features a semantic, AI-based search function that allows for content-driven access to publications. Users can not only search for specific topics or keywords but are also automatically shown thematically related documents. This significantly increases the actual and documentable findability of individual publications and enables searchability that meets the standards referenced in EPO case law on the public accessibility of library holdings (e.g., T 834/09, T 314/99). Access to the information is thus ensured not only formally but also in practice.
According to Art. 54(2) EPC, the state of the art comprises everything made available to the public before the filing date. Consistent EPO case law, in particular decision G 1/92, clarifies this provision by stating that an item is made available to the public if there was no confidentiality obligation and a skilled person could access the information using ordinary means (G 1/92, OJ EPO 1993, 277). Decision T 482/89 also emphasizes the principle of free evaluation of evidence, according to which any means of evidence that appears suitable to establish the facts can be taken into account (T 482/89, OJ EPO 1992, 646).
The EPO Guidelines confirm that online publications can constitute prior art, provided the publication date is verifiable and access was not restricted. Section G-IV, 7.5 of the Guidelines states that even content behind a paywall may be considered public if no confidentiality obligation exists and access is generally available (EPO Guidelines G-IV, 7.5). Therefore, a fee-based publication is not inherently excluded from the public domain. The EPO draws a parallel to purchasing a textbook or journal article, which also requires a fee. The key requirement is that access is not subject to selection procedures or individual approval but is open to anyone willing to pay. This applies to the Proofbox model.
The main challenge lies in proving the time and immutability of the publication. The EPO emphasizes the need for credible proof of the publication date, evaluated under the balance of probabilities standard (EPO Guidelines G-IV, 7.5.2). This does not require absolute certainty, but a convincing demonstration that the publication occurred at the stated time. Mere assertions without supporting evidence are insufficient; on the other hand, mathematical proof is not required. T 750/94 stresses that in serious matters such as the validity of a prior publication, stringent standards apply to the evidentiary value of submitted documentation (T 750/94, OJ EPO 1998, 32).
In the case of Proofbox, the publication date is proven by a digital timestamp generated by a qualified trust service such as A-Trust or Signteq. These timestamps are eIDAS-compliant (EU Regulation No. 910/2014) and therefore meet European requirements for qualified electronic time evidence. The integration of the document hash into the timestamp also ensures document integrity. This practice complies with ISO/IEC 18014 and ISO/IEC 27001 and forms the basis for a reliable chain of custody for content and date.
Moreover, each page of the document embeds the corresponding hash value, enabling complete traceability of any changes. Availability is monitored server-side at least twice daily and recorded in a tamper-proof log. Each publication is accessible via a permanent, individualized URL, thereby fulfilling the public accessibility requirement under decision T 2/09 (PHILIPS), which states that documents findable through web search engines are in principle publicly available (T 2/09, point 4.8).
One residual risk lies in how different EPO boards assess such evidence. Decision T 1961/13 (COLUMBIA UNIVERSITY) illustrates that the EPO may apply a strict standard when assessing public availability. In that case, the online availability of a document was denied because the archival mechanisms and exact date could not be sufficiently substantiated (T 1961/13, points 4 and 5). This decision shows that even a plausible Google index entry is not enough without reliable archive sources or timestamp evidence.
Under U.S. patent law, the relevant standard is 35 U.S.C. § 102(a)(1), which includes any "printed publication" made publicly available before the effective filing date. According to MPEP § 2128, online publications must be both publicly accessible and permanently available. A paywalled publication is permissible if access is possible and not restricted by a confidentiality obligation. The USPTO accepts digital timestamps and archived content under certain conditions but requires objective verifiability of the date.
Proofbox provides a robust level of documentation by U.S. standards through its eIDAS-compliant timestamping, hash protection, public URL, SEO optimization, and logging of continued online availability. However, in a legal dispute, a U.S. court or the USPTO would need to determine whether the technology and evidence chain used meet the authentication and accessibility requirements. U.S. case law on online publications tends to be pragmatic and emphasizes archived and verifiable sources (e.g., Wayback Machine, DOI, or published metadata).
Additionally, the new Unified Patent Court (UPC) must be considered. The UPC follows the EPC in substantive law and applies its own procedural rules. According to Rule 262.2 of the UPC Rules of Procedure, the principle of free evaluation of evidence also applies. Electronic documents are explicitly admissible as evidence if their authenticity and relevance can be sufficiently demonstrated. The combination of eIDAS-compliant timestamps, documented public availability, and secure logging suggests that a Proofbox publication would be admissible as evidence before the UPC, particularly if a technical expert is consulted to validate the digital evidence. Still, some uncertainty remains as the UPC has not yet ruled on such internet publications.
Ultimately, the admissibility of Proofbox documents in opposition or revocation proceedings before the EPO, the UPC, or in U.S. court proceedings depends on the persuasive power of the submitted evidence. The EPO operates under the principle of free evaluation of evidence, where each item is assessed on its merits (T 482/89). The use of a qualified timestamp, tamper-proof archival mechanisms, and documentation of public accessibility speak for strong evidentiary value. However, legal uncertainty remains as no court decision to date has addressed a publication mechanism comparable to Proofbox.
In summary, the technical and organizational measures implemented by Proofbox are, under current European, UPC, and U.S. law, suitable to produce an online publication that can qualify as prior art. This is conditional on consistent proof of the publication date, content, immutability, and public accessibility in each individual case. The evaluation of evidence remains subject to the competent court or examining authority. Based on the existing case law—particularly G 1/92, T 482/89, T 750/94, T 2/09, and T 1961/13—and the UPC Rules of Procedure, a legally valid recognition of such a publication as prior art is likely, though not guaranteed. U.S. requirements are similar, focusing on objective verifiability and permanent availability. Proofbox’s measures are aligned with these standards, though ultimately subject to case-specific judicial scrutiny.
Notice
Due to legal limitations under some jurisdictions unfair competition law, the identity of the European patent attorney cannot be disclosed publicly. If you have questions or wish to discuss legal aspects of enforceability or prior art recognition, please contact us via our contact form. We will be happy to connect you with the expert behind this analysis.
Alternatively, you can also consult any registered European or US patent attorney for further questions through the following public registers:
Disclaimer
The information provided in this blog and on this page is for general informational purposes only and does not constitute legal advice. Proofbox Services FZCO is not a law firm and is not authorized to provide legal counsel or act as a legal representative in any jurisdiction. The content herein is not intended to replace professional legal consultation, and users are strongly advised to seek independent legal advice from a qualified attorney before making any decisions related to intellectual property, defensive disclosures, or publication strategies. While we aim to keep the information up to date and accurate, no guarantee is given as to the completeness, accuracy, or currentness of the content provided. Proofbox Services FZCO expressly disclaims any liability for errors, omissions, or outdated references and assumes no responsibility for any actions taken or not taken based on the information on this page and any pages of our Website and Blog. Using this site does not create any form of attorney-client relationship, and Proofbox Services FZCO assumes no legal liability for reliance on the materials presented. Please also refer to our Terms and Conditions and Privacy Policy, which govern the use of this website and our services.
