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Law & practice

Notice from the European Patent Office concerning internet citations

OJ EPO 2009, 456

1. Summary

The present notice sets out the practice followed at the EPO when citing documents retrieved from the internet in both the European and the PCT procedure.

2. Search on the internet

The search for prior art can also cover internet sources including online technical journals, online databases, or other websites. The extent of such internet searches depends on the individual case, but in some technical fields a systematic internet search will regularly be necessary. Especially in fields related to information or software technology, searches bypassing the internet will often not yield the most relevant prior art.

3. Internet disclosures

As a matter of principle, disclosures on the internet form part of the state of the art according to Art. 54(2) EPC and Art. 33(2) PCT (for the latter, see the PCT Guidelines 11.13). Information disclosed on the internet or in online databases is considered to be publicly available as of the date the information was publicly posted. Internet websites often contain highly relevant technical information. Certain information may even be available only on the internet from such websites. This includes, for example, online manuals and tutorials for software products (such as video games) or other products with a short life cycle. For the sake of a valid patent it is hence often crucial to cite publications only obtainable from such internet websites.

3.1 Establishing the publication date

Establishing a publication date has two aspects. It must be assessed separately whether a given date is indicated correctly and whether the content in question was indeed made available to the public as of that date.

The nature of the internet can make it difficult to establish the actual date on which information was made available to the public: for instance, not all web pages mention when they were published. Also, websites are easily updated yet most do not provide any archive of previously displayed material, nor do they display records which enable members of the public – including examiners – to establish precisely what was published and when.

Neither restricting access to a limited circle of people (e.g. by password protection) nor requiring payment for access (analogous to purchasing a book or subscribing to a journal) prevents a web page from forming part of the state of the art. It is sufficient if the web page is in principle available without any bar of confidentiality.

Finally, it is theoretically possible to manipulate the date and content of an internet disclosure (as it is with traditional documents). However, in view of the sheer size and redundancy of the content available on the internet, it is considered very unlikely that an internet disclosure discovered by an examiner has been manipulated. Consequently, unless there are specific indications to the contrary, the date will be accepted as being correct.

3.2 Standard of proof

When an internet document is cited against an application or patent, the same facts are to be established as for any other piece of evidence, including standard paper publications (see Guidelines C-IV, 6.1). This evaluation is made according to the principle of "free evaluation of evidence" (see T 482/89, OJ 1992, 646, and T 750/94, OJ 1998, 32). That means that each piece of evidence is given an appropriate weighting according to its probative value which is evaluated in view of the particular circumstances of each case. For assessing these circumstances, the balance of probabilities will be used as the standard of proof, as generally applied by the boards of appeal. According to this standard, it is not sufficient that the alleged fact (e.g. the publication date) is merely probable; the examining division must be convinced that it is correct. It does mean, however, that proof beyond reasonable doubt ("up to the hilt") of the alleged fact is not required.

In many cases, internet disclosures contain an explicit publication date which is generally considered reliable. Such dates are accepted at face value and the burden of proof will be on the applicant to show otherwise. Circumstantial evidence may be required to establish or confirm the publication date (see 3.4). If the examiner comes to the conclusion that – on the balance of probabilities – it has been established that a particular document was available to the public at a particular date, this date is used as publication date for the purpose of examination.

3.3 Burden of proof

It is a general principle that, when raising objections, the burden of proof lies initially with the examiner. This means that objections must be reasoned and substantiated, and must show that, on the balance of probabilities, the objection is well-founded. If this is done then it is up to the applicant to prove otherwise - the burden of proof shifts to the applicant.

If an applicant provides reasons for questioning the alleged publication date of an internet disclosure, examiners will have to take these reasons into account. If examiners are no longer convinced that the disclosure forms part of the state of the art, they will either have to present further evidence to maintain the disputed publication date or will not use this disclosure further as prior art against the application.

If an applicant contests the publication date of an internet disclosure with no reasoning or merely with generic statements about the reliability of internet disclosures, this argument will carry minimal weight and is therefore unlikely to sway the examiner’s opinion.

While the dates and content of internet disclosures can be taken at face value, there are of course differing degrees of reliability. The more reliable a disclosure, the harder it will be for the applicant to prove that it is incorrect. The following sections look at the reliability of various popular types of internet disclosures.

3.3.1 Technical journals

Of particular importance for examiners are online technical journals from scientific publishers. The reliability of these journals is the same as that of traditional paper journals, i.e. very high.

It should be noted that the internet publication of a particular issue of a journal may be earlier than the date of publication of the corresponding paper version. Furthermore, some journals pre-publish on the internet manuscripts which have been submitted to them, but which have not yet been published, and in some cases before they have even been approved for paper publication. If the journal then does not approve the manuscript for publication, this pre-publication of the manuscript may be the only disclosure of its content. It should be noted that the pre-published manuscript may differ from the final, published version. The two documents will be treated as separate disclosures, each with its own publication date.

3.3.2 Other "print equivalent" publications

Many sources other than scientific publishers are generally deemed to provide reliable publication dates. These include for example publishers of newspapers or periodicals, or television or radio stations. Academic institutions, international organisations, public organisations and standardisation bodies also typically fall into this category.

Some universities host so-called e-print archives to which authors submit reports in electronic form on research results before they are submitted or accepted for publication by a conference or journal. In fact, some of these reports are never published anywhere else. Some such archives trawl the internet to automatically retrieve publications which are publicly available from researchers' web pages.

Companies, organisations or individuals use the internet to publish documents that had previously been published on paper. These include manuals for software products such as video games, handbooks for products such as mobile phones, product catalogues or price lists and white papers on products or product families. Evidently, most of these documents address the public – e.g. actual or potential customers – and are thus meant for publication. Hence the date given can be taken as a date of publication.

3.3.3 Non-traditional publications

The internet is also used to exchange and publish information in ways which did not exist before, via, for example, Usenet discussion groups, blogs, e-mail archives of mailing lists or wiki pages. Documents obtained from such sources also constitute prior art, although it may be more involved to establish their publication date and their reliability may vary.

Computer-generated timestamps (usually seen, for example, on blogs, Usenet or the version history available from wiki pages) can be considered as reliable publication dates. While such dates could have been generated by an imprecise computer clock this will be weighed against the fact that in general many internet services rely on accurate timing and will often stop functioning if time and date are incorrect. In the absence of indications to the contrary, the frequently used "last modified" date can be treated as the publication date.

3.4 Disclosures which have no date or an unreliable date

Where an internet disclosure is relevant for examination but does not give any explicit indication of the publication date with the text of the disclosure or if an applicant has shown that a given date is unreliable, the examiner may try to obtain further evidence to establish or confirm the publication date.

In particular, this evidence may come from an internet archiving service, the most prominent being the internet archive accessible through the so-called "Wayback Machine" ( The fact that the internet Archive is incomplete does not detract from the credibility of the data it does archive. It is also noted that legal disclaimers relating to the accuracy of any information supplied are routinely used and these disclaimers will not be taken to reflect negatively on the websites' actual accuracy.

If no date can be obtained (other than the date of retrieval by the examiner, which will be too late for the application in question), the disclosure cannot be used as prior art during the examination. If the examiner considers that a publication, although undated, is highly relevant to the invention and can therefore be considered to be of interest to the applicant or third parties, he may choose to cite the publication in the search report as an L document (B-X, 9.2 (viii)). The search report and the written opinion will explain why this document was cited. Citing the disclosure will also make it citable against future applications using the date of retrieval as the date of publication.

Documents indicating or establishing the publication date of a document from the internet will also be cited in the search report as L documents (B-X, 9.2 (viii) (b)).

4. Internet disclosures submitted by a party to opposition proceedings

The publication date of internet disclosures submitted by a party to opposition proceedings are assessed according to the same principles as are applied in examination proceedings, i.e. they will be assessed in view of the specific circumstances of the case. In particular, the timing of the submission as well as the interests of the party submitting the disclosure will also be taken into account.