Prior Art Definition: Scope, Dates, and Disclosure

Legal prior art definition under the EPC

Under EPC Article 54(2), the state of the art comprises everything made available to the public, before the filing date of the European patent application, through a written or oral description, by use, or in any other way.¹ A valid priority claim can change the relevant date for subject matter entitled to that priority.

This definition has three connected elements: time, public availability, and disclosed content. A searcher must test all three rather than treating a document date or a search-engine result as sufficient on its own.

Element 1: the relevant date

For EPC Article 54(2), the reference point is the filing date, subject to a valid priority claim. The practical question is not simply whether a source looks old. The reviewer must establish that the relevant content was publicly available before the date that applies to the claimed subject matter.

A disclosure after that relevant date is generally not Article 54(2) prior art against the application. However, later-published European applications with an earlier filing or valid priority date may fall within the special rule in Article 54(3), discussed below.

Element 2: public availability

Public availability does not depend on widespread readership. Under the EPO approach, subject matter may be public when a member of the public could gain knowledge of it and no confidentiality duty restricted use or dissemination.³ Conversely, an internal document or use under an effective express or implied secrecy obligation may not be public.

Element 3: what was actually disclosed

The relevant disclosure is the information that the public could obtain from the document, presentation, product, use, or other event. A title, abstract, screenshot, sales record, or archived page may establish only part of the picture. The reviewer still needs to identify the technical teaching and determine whether it was available clearly enough for the legal question being assessed.

Three modes of prior art disclosure

1. Written or publication disclosure

Written disclosures can include published patent documents, journal articles, books, conference papers, theses, standards, product manuals, technical specifications, and publicly accessible online materials. The category is broad, but the same core questions apply: what content was available, to whom, and on what date?

A company report distributed only within a confidential group is not automatically public merely because it exists in writing. In contrast, a technical manual supplied without a confidentiality restriction, a publicly accessible thesis, or a published patent application may form part of the prior art if the remaining legal conditions are met.

2. Disclosure by use, sale, exhibition, or demonstration

A use-based allegation requires a fact-specific review. The EPO’s 2026 Guidelines direct reviewers to determine when the alleged use occurred, what was used, and the circumstances that show whether and to what extent the subject matter became public.³

An unconditional commercial sale can make knowledge obtainable from a product public. However, current EPO guidance distinguishes intrinsic product features from characteristics that arise only through selected outside conditions, and it also recognizes that public access, confidentiality, and the nature of the technical teaching matter.³ Accordingly, treating every sale as disclosure of every feature is too broad.

3. Oral, internet, and other disclosures

Lectures, broadcasts, demonstrations, websites, social posts, code repositories, product pages, and other online materials can be relevant. For internet evidence, the EPO separates two questions: whether the stated date is reliable and whether the particular content was publicly available on that date.⁴

Preserve the URL, the content reviewed, visible dates, repository history, archive records, and surrounding context. A screenshot taken today proves what the reviewer saw today; it does not by itself prove what was online before the relevant date. EPO guidance identifies archive records, modification histories, repository timestamps, forum dates, indexing information, and mirrored versions as possible corroborating material.⁵

Special case: conflicting European applications

EPC Article 54(3) adds the content of certain European patent applications whose filing dates are earlier than the relevant date but which were published on or after that date.¹ These applications are often described in practice as conflicting applications or earlier European rights.

An illustrative timeline

• Applicant A files a European application in January.
• Applicant B files a European application containing overlapping subject matter in March.
• Applicant A’s application is published after Applicant B’s filing date.

Although A’s application was not publicly available when B filed, it may become relevant under Article 54(3) if the statutory conditions, content, dates, and territorial requirements are satisfied. The actual assessment must also account for valid priority and the precise subject matter disclosed.

Why the distinction matters

Under EPC Article 56, Article 54(3) documents are not considered when deciding inventive step; their role is limited to novelty.⁶ Searches should therefore examine applications published around and after the relevant date, but reviewers must label the legal category correctly rather than calling every later publication ordinary public prior art.

Filing date and priority date: determine the benchmark

What a priority right can do

Under EPC Article 87, a person who duly files a qualifying first application may claim priority for a European application concerning the same invention during a twelve-month period.⁷ A priority date counts as the filing date for EPC prior-art analysis only when the priority is valid and only for the subject matter entitled to it.

Consequently, a single application may require more than one relevant-date analysis when claims or claim elements have different priority support. Newly added subject matter does not automatically receive the earlier date.

How to apply the date in a patentability search

1. Identify the application and every claimed priority.
2. Confirm the filing and priority documents.
3. Map the searched subject matter to the disclosure supporting the priority claim.
4. Flag intermediate publications and later-published earlier applications separately.
5. Ask a qualified professional to resolve disputed entitlement or validity.

Prior art definition and practical search scope

A legally relevant search scope should reflect the technology, target jurisdictions, applicable dates, and likely disclosure channels. No source or fixed checklist guarantees completeness.

Core source categories to plan

WIPO’s PATENTSCOPE provides access to published PCT applications, participating national and regional collections, and non-patent literature, with search criteria including keywords and IPC.⁸ Espacenet supports searching patent publications and offers classification and related patent-information tools.⁹ These examples are complementary sources, not a completeness ranking.

Context-dependent supplements

Before expanding the search, Eureka IP Drafting’s Invention Disclosure workflow can turn rough technical notes into a structured disclosure and highlight missing details or possible inventive points.¹⁰ That separate pre-filing workflow can help define what needs searching; it does not establish public availability or the legal effect of a reference.

Judgment of key prior art boundary issues

Q1: Does technology used only inside a company count as prior art?

Confidential internal use is generally not public under the EPC. However, a disclosure to a customer, supplier, visitor, or partner may require closer analysis of access, express or implied confidentiality, and what technical information the recipient could obtain. The absence of a written NDA does not automatically settle whether an implied duty existed.

Q2: Does code in a private repository count?

A repository that was genuinely inaccessible to the public and limited by confidentiality is different from a publicly accessible repository. If access later becomes public, the reviewer must establish when the relevant files became available, what version was available, and whether the code disclosed the claimed technical teaching. A repository label alone does not answer those questions.

Q3: Can an inventor’s social-media post become prior art?

It can be relevant if the post made the technical information available without confidentiality before the applicable date. The audience settings, access restrictions, content, publication history, and evidence of timing all matter. In addition, jurisdiction-specific grace periods or non-prejudicial-disclosure rules may affect the result, so teams should not assume that an inventor’s own post is either always fatal or always excused.

Q4: Can a crowdfunding product page count?

A publicly accessible crowdfunding page may be a written internet disclosure when its technical content and date can be established. Yet a marketing statement that identifies only a desired result may not disclose the technical features required for a novelty analysis. Preserve the dated page and supporting material, then compare the actual disclosure with the claim under the applicable law.