Prior art

Prior art is information relevant to whether an invention meets the requirements for patent protection. In the ordinary case, it includes what was made available to the public before the relevant filing date or valid priority date. Earlier rights in trade marks or designs raise different questions and should not be treated as patent prior art without regard to the applicable legal regime.

How prior art affects a patent

A patent publication, scientific paper, public presentation, product demonstration or prior commercial use may disclose relevant technical information. The evidence must establish what was disclosed, when, and whether the public could access it. A confidential disclosure is not automatically a public disclosure.

For novelty, the analysis asks whether the claimed subject matter is directly and unambiguously disclosed in a single prior-art disclosure, read by the skilled person. Inventive step raises a different question: whether the invention was obvious in light of the relevant state of the art. These inquiries should not be conflated.

Conducting a prior-art search

1. Define the technical subject matter. Identify the essential features and appropriate search terms, synonyms and patent classifications.
2. Search patent and non-patent literature. Patent databases maintained by the EPO, WIPO and USPTO can be combined with scientific publications, manuals and product documentation.
3. Screen the results. Identify potentially relevant publications and uses, and record their dates and provenance.
4. Analyse the disclosure. Compare each relevant feature with the document or use, distinguishing what is actually disclosed from what is inferred.
5. Prepare a reasoned assessment. Explain which objections the evidence may support and what remains to be established.

A search cannot guarantee that every relevant disclosure has been found. In litigation, its value also depends on whether the resulting documents can be authenticated and linked to the applicable critical date.

Frequently asked questions

What makes a disclosure novelty-destroying?

It must disclose the claimed subject matter under the applicable novelty test. Separate disclosures cannot simply be assembled as a mosaic to establish lack of novelty. The precise teaching of the document or use matters more than a similarity in general purpose.

Can an oral disclosure be prior art?

Yes. Under Article 54 EPC, written and oral descriptions, use and other forms of public disclosure can form part of the state of the art. Proving the content, date and circumstances of access is often the central difficulty.

Can an unpublished application be relevant?

Earlier-filed European applications published later may qualify under Article 54(3) EPC, subject to its conditions. Such material is relevant to novelty, but is excluded from the inventive-step assessment by Article 56 EPC. This special rule should not be generalised to every unpublished application worldwide.

Prior art in patent litigation

A revocation strategy requires a claim-by-claim analysis, a reliable chronology and a clear account of the technical teaching relied upon. See our entries on patent claims and revocation actions.

Related resources

UPC Litigation Watch · Unified Patent Court

Dhenne Avocats represents clients in patent disputes before the French courts and the UPC. Discuss a dispute with the firm.

This glossary entry provides general information and is not advice on an individual matter.

This entry focuses on individually identified prior disclosures. The state of the art entry addresses the legally relevant body of information to which they may belong.