Patents: standard of proof for internet prior art




The European Patent Office (EPO) appeals board has considered the standard of proof required to show that an internet disclosure had been made available to the public before the priority date of a patent, and is prior art.


In November 2016, the EPO published guidance which highlighted the potential difficulties in establishing the actual date on which information was made available to the public on the internet. Not all webpages mention when they were published and websites are easily updated but most do not provide any archive of previously displayed material to establish precisely what was published and when.

The EPO has held that, to establish that an internet disclosure formed part of the state of the art, the same strict standard of proof as for prior use or prior oral disclosure, that is, beyond any reasonable doubt, had to be applied (Neoteric Technology Limited T-1134/06). Circumstances which allowed the determination of availability to the public might also  include factors that had a bearing on the reliability of the information.


A European patent application claimed a priority date of 24 May 2002. The EPO Examining Division refused the application for lack of novelty over a prior art document. This document was retrieved from the internet in December 2003, and had been included in the international search report. 

O challenged the decision on the basis that prior publication had not been proved, arguing that the date of January 2002 on the cover page of the document was not proof of availability to the public at that date. 

The EPO Examining Division refused to admit the evidence supporting this challenge as it was filed too late and did not show that the document had not been published before the priority date. O appealed.


The EPO appeals board allowed the appeal and remitted the case for further prosecution. It held that the EPO Examining Division had applied both the wrong standard of proof and the wrong procedure for establishing proof that the internet document was prior art. 

EPO case law on the standard to prove that an internet disclosure was prior art was inconsistent. There were different and irreconcilable views in appeal case law about the proper standard of proof relating to the issue of availability to the public, particularly internet disclosures.

While these standards of proof differed conceptually, in most cases this need not lead to divergent results if the standard of balance of probabilities was applied with some qualification. Numerous decisions applied the standard of balance of probabilities, but made it clear that slightly tipping the balance of probabilities was insufficient when assessing the public availability of prior art.

The facts on which any finding of public availability was based had to be established with a sufficient degree of certainty in order to convince the EPO, in view of all the relevant evidence, that they had indeed occurred, even if the determination was made on the basis of probabilities rather than beyond any reasonable doubt.

When raising objections, the burden of proof lay initially with the EPO Examining Division. Objections had to be reasoned and substantiated, and had to show that, on the balance of probabilities, they were well-founded. With respect to the publication date of a cited document, at least prima facie evidence was required, which was sufficient, on its own, to establish a fact or to raise a presumption of the truth of a fact unless controverted. If the objection was properly raised, it was then up to the applicant to prove otherwise or to submit evidence to displace the prima facie evidence. If the applicant successfully challenged prima facie evidence concerning a fact, for example, the nominal publication date of a document, the burden of proof shifted back to the EPO Examining Division to establish that the document was made available to the public.

Here, the document was retrieved from the internet on 15 December 2003, more than 18 months after the priority date of the application. Neither the search report nor the first communication, which cited the document, explained why the document was considered to have been publicly available before the priority date.

With internet disclosures, the absence of explanation was acceptable only where, in the circumstances, it was self-evident why the document was considered to have become publicly available before a specific date. Those circumstances could include the nature and reliability of the website from which the document was retrieved as well as intrinsic evidence deduced from information in the document itself.

The only circumstantial evidence on which the EPO Examining Division relied for its assumption that the document was made publicly available in January 2002 was the date on the cover page of the document. However, this date was imprecise and the document did not specify this date as its publication date. It was at best prima facie evidence that the document was created in January 2002, but not that it was made available to the public on that date. The commercial website from which the document was retrieved was not a source generally deemed to provide reliable publication dates, such as the websites of scientific publishers. 

As neither the information provided in the document itself nor its source of retrieval allowed, on their own, to conclude with sufficient certainty that the document was publicly available in January 2002, the document should not have been cited as prior art by the EPO Examining Division without further explanation and evidence. As the objection to patentability was not properly raised, O was not obliged to submit evidence against the assumed publication date.

The EPO Examining Division had incorrectly refused to admit the evidence put forward by O at the oral hearing, which cast doubt on the assumption that the document had been published before the priority date.


While this decision establishes a less stringent standard of proof for proving publication of an internet disclosure before a relevant priority date, it does mean that patent searchers and examiners must do more work before citing that disclosure as prior art than merely relying on an unspecified date on the document itself. The increasing trend to publish technical documents only online means that this issue will become increasingly important in patent practice, both prosecution and litigation.

Case: Oracle International Corporation T-0545/08.

First published in the May 2017 issue of PLC Magazine and reproduced with the kind permission of the publishers.  Subscription enquiries 020 7202 1200.