T 2403/11 - Contradicting yourself

EPO T 2403/11

For the decision, click here. (Published already on 23.07.2014)

Key points

• This decision was published 23.07.2014 and is discussed in OJ 2014, SE4. 
• According to the EPO headnote, "An ill-defined parameter in a claim may lead to insufficiency of disclosure if this parameter is relevant for solving the problem addressed in the patent. If, in such a situation, the patent specification states that the ill-defined parameter is relevant and the patent proprietor initially argued along those lines, then, normally it cannot argue, later on in the proceedings, that this parameter does not matter."
• However, the actual wording of the Board is not restricted to parameters - "The proprietor is not free to choose a particular approach when drafting the patent and when arguing its case, and then to change it later on when it realises that this approach might fail."
• This statement may also be useful in case the patent proprietor initially argues that a technical effect is obtained by a broad claim 1 and later restricts the claim.  

Reasons for the Decision

[...]

2.6.2 The board does not find this argument acceptable. The proprietor is not free to choose a particular approach when drafting the patent and when arguing its case, and then to change it later on when it realises that this approach might fail. So if the proprietor (and in the present case appellant) chooses to include a statement when drafting the patent that, in order to solve the problem underlying the patent, the coating composition must have a certain viscosity, then normally it cannot argue, later on in the proceedings, that in fact the viscosity does not matter.