6.6.9 Analytical measuring methods

Where it is obvious that a skilled person would select a particular analytical measuring method, (none being disclosed in the patent), balancing its simplicity and convenience against the required accuracy, the requirements of Art. 83 EPC are met (see e.g. T 492/92). This is the case even if the two different analytical methods proposed by the patentee give significantly different results with the same composition. It also suffices if the person skilled in the art would assume that it was most likely that a certain method was used and this assumption could be tested in the light of the information given in the examples of the patent in suit (T 143/02). However, where there are different measuring methods which do not always lead to the same result, this can amount to an undue burden, as in T 225/93. In T 930/99, the board considered T 225/93 inapplicable, as there was only one measurement method before them. The respondent's argument that there would be legal uncertainty, since third parties would not know whether they were working within or outside the range specified, was clearly an argument based on lack of clarity, which was not a ground of opposition and so could not be considered (see also in this chapter II.C.8.2.).

See also chapter II.C.5.5.1 "Ambiguous parameters", where the issue of methods of determining parameters is likewise addressed.