Art. 55 EPC specifies that a disclosure of the invention shall not be taken into consideration for the application of Art. 54 EPC, if it occurred no earlier than six months preceding the filing of the European patent application and if it was due to, or in consequence of: (a) an evident abuse in relation to the applicant or his legal predecessor, or (b) the fact that the applicant or his legal predecessor has displayed the invention at an official, or officially recognised, international exhibition.

In consolidated cases G 3/98 (OJ 2001, 62) and G 2/99 (OJ 2001, 83) the Enlarged Board ruled that, when calculating the six-month period under Art. 55(1) EPC 1973, the relevant date is that of the actual filing of the European patent application, not the priority date.

In T 173/83 (OJ 1987, 465) the board ruled that there would be evident abuse within the meaning of Art. 55(1)(a) EPC 1973 if it emerged clearly and unquestionably that a third party had not been authorised to communicate to other persons the information received. Thus there was abuse not only when there was the intention to harm, but also when a third party acted in such a way as to risk causing harm to the inventor, or when this third party failed to honour the declaration of mutual trust linking him to the inventor.

In T 585/92 (OJ 1996, 129) the board found that where a patent application was published early by a government agency as a result of an error, this was not of necessity an abuse in relation to the applicant within the meaning of Art. 55(1)(a) EPC 1973, however unfortunate and detrimental its consequences might turn out to be. In order to determine whether there was an abuse within the meaning of Art. 55(1)(a) EPC 1973, the state of mind of the "abuser" was of importance.

In T 436/92 the board found that deliberate intention to harm the other party would constitute evident abuse, as would also, probably, knowledge of the possibility of harm resulting from a planned breach of confidentiality. The state of mind of the "abuser" was of central importance (confirming T 585/92). The board held that the appellant had not proven, on the balance of probability, that the publications had occurred in violation of the tacitly agreed confidentiality. In other words, the publication was not an evident abuse within the meaning of Art. 55(1) EPC 1973.