In T 632/95 the board confirmed that the burden of proving that a document had been received lay with the party submitting the document just as, vice versa, the EPO bore the burden of proving receipt of the documents it issued.
It is the appellant who is responsible for ensuring receipt of the notice of appeal and who, therefore, bears the burden of proving that it was actually filed. Otherwise, the EPO would have to prove that it had not received it, but since something which has not taken place cannot readily be proved, it cannot be expected to do so. It is for the same reason that, in disputes involving reverse circumstances, the EPO bears the burden of proving that its correspondence was received by the addressee. Whereas the EPO secures evidence of receipt by sending correspondence relating to deadlines by registered mail with advice of delivery, senders of correspondence addressed to the EPO can choose from several other options readily providing them with proof of receipt, including despatch of pleadings by registered mail with advice of delivery or by electronic means, such as fax or email, with an automatically printed or electronic confirmation of receipt. This wide variety of basically equivalent means of despatching correspondence to the EPO does not interfere with the sender's obligation to prove receipt in the event of dispute. A different treatment cannot take place on the basis, for instance, that a document has or may have been lost due to negligence on the part of the EPO staff. As a result, senders must choose the form of delivery which, in adverse circumstances, can most readily be proven. If they opt for a form of delivery making it difficult to prove receipt, they do so at their own risk (T 2454/11).
In this respect, it has to be observed that a party submitting that something has not happened is faced with the difficulty of proving this allegation. The party can essentially presume what could have happened or what normally would have been done if a letter had been received, in order to cast doubt upon the EPO's evidence, but it is hardly ever possible to file compelling evidence that the letter was not received. The EPO is also in a difficult situation if an applicant submits that it has not received a communication. The EPO then has to start enquiries with the postal services and rely on the information obtained. Since details are not given, this information is usually unsatisfactory. After a certain period the relevant information may not even be obtainable at all. However, this ought not to be to the detriment of the applicant, specifically not where communication noting a loss of rights is concerned. These problems could be avoided if such communications were delivered by registered letter with advice of delivery (J 9/05 and J 18/05).
According to the German version of R. 126 (2) EPC (former R. 78(2) EPC 1973), the EPO must in a case of doubt ("im Zweifel") establish the date on which the letter was delivered to the addressee. In T 247/98 the board decided that, when establishing the meaning of the term "im Zweifel" in the German version of R. 78(2) EPC 1973, account should be taken of the French and English versions, which assumed that there was a dispute ("en cas de contestation", "in the event of any dispute"). From the general principles concerning the burden of presentation which fell on the parties, it followed that a party seeking the application of a legal provision favourable to its interests had to set out the facts justifying such application, even if it did not ultimately bear the burden of proof for those facts. Although, in the event of a dispute within the meaning of R. 78(2) EPC 1973, the burden of proof for the date of delivery fell on the EPO, this could not be taken to mean that a party wishing to rely on the late delivery of a letter from the EPO had no obligation to contribute to the clarification of circumstances within its own sphere of activity but could sit back, as it were, and wait to see whether the EPO succeeded in ascertaining when the letter had been delivered to the party. A dispute ("Zweifel" in the German version) within the meaning of this rule could only arise if it was maintained that a letter had in fact been received more than ten days following its posting.
Under the EPC, the date of receipt of an item at the EPO is critical when assessing compliance with a time limit. The burden of proof that a filing has been effected falls on the filing party. The impossibility of furnishing proof of a higher probability that an item was filed than that it was not filed, must therefore count against the filing party – as found by the board in T 1200/01. In this particular case, the available evidence did not convince the board that there was a higher degree of probability that the alleged filing had taken place than that it had not. Contrary to the decision in T 1200/01, the board in T 2454/11 found that the strict allocation of the burden of proof to the sender of correspondence addressed to the EPO could not be mitigated by weighing up the probability of receipt. Such an approach to examining the issue would seriously jeopardise legal certainty and water down the standard of legal clarity required in formal procedures such as those before the EPO. The need in disputed cases to interpret the vague legal notion of probability and the judicial exercise of ascertaining whether a greater or lesser likelihood was to be presumed would result in a wide variety of possibly contradictory approaches to the issue. Such inconsistencies would run counter to the need for a transparent and straightforward procedure and therefore had to be avoided in the interests of the public and third parties involved in the proceedings. Consequently, a high probability of delivery could not be a factor in deciding whether correspondence had actually been received. Rather, it was for the sender to prove such receipt to the board's satisfaction.
In J 10/91 the board held that if a letter and attached cheque in payment of a fee, had been lost without further evidence or any high probability that it had been lost in the EPO, the risk was then borne by the sender. Even conclusive evidence that something had been posted could not be treated as sufficient to prove that a document had been received by the EPO. In this respect, the board in J 8/93 stated that if the post failed to deliver a document, the applicant would suffer the consequences for failing to file that document.
Under R. 125(4) EPC (former R. 82 EPC 1973), the burden of proof that documents have been duly notified to the parties lies with the EPO. In T 580/06 the question was raised whether the "OK" reference on the transmission sheet of a faxed document was sufficient proof of receipt. In the absence of relevant EPO case law, the board drew on procedural principles developed for notification by fax in German law, the fax transmission in question having arisen in the territory of the Federal Republic of Germany. In line with the German case law on that issue, the board recognised that an up-to-date objective assessment of the question of receipt of a fax by the addressee needed to take into account the technology underlying faxes. The high reliability of this technology nowadays was based amongst other things on established technical protocols, according to which modern fax machines operated. On the basis of various considerations the board reached the conclusion that the "OK" reference on the transmission sheet of a fax was to be regarded as proof of an error-free and complete transmission, through which the fax had entered into the area of responsibility of the representative. Once the fax had entered the area of responsibility of the addressee indicated by the reference "OK", then a transfer of risk took place so that the recipient bore the risks in his own sphere.