The law on this seems now to have been established by the decisions in T 286/10 and T 2227/11, which were endorsed more recently in T 1711/11, T 353/14, T 545/08 and T 1589/13. Those decisions also cited the EPO practice set out in its notice concerning internet citations (OJ 2009, 456 to 462) and the Guidelines for Examination at the EPO (G‑IV, 7.5 – (unchanged in) November 2018 version): 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. This evaluation is made according to the principle of "free evaluation of evidence". That means that each piece of evidence is given an appropriate weight according to its probative value, which is evaluated in view of the particular circumstances of each case. The standard for assessing these circumstances is the balance of probabilities. 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.

In short, the appropriate standard of proof for internet citations is the "balance of probabilities".

The conclusion of the earlier decision T 1134/06 that the stricter standard of proof "beyond reasonable doubt" had to be applied to internet disclosures has been refuted.

For further information, see in this chapter I.C.3.2.3 "Internet disclosures" and in chapter III.G.4.2.3 "Archives and internet publications".