T 1579/08 – Trouble With The Greek

If accidentally in your priority document you have referred to mm instead of μm and if you have rectified the error in the application claiming the priority, can you still validly claim priority? That is the question the Board had to deal with in the present decision.

Claim 1 of the main request read:

1. A softening laundry detergent tablet comprising clay and laundry surfactant, wherein the clay consists of smectite clay, and wherein the tablet is a compressed mass of particles, and at least 50% by weight of the clay is present as granules which have a size of at least 100 μm, the clay granules containing at least 50% by weight of the clay.

[1.2.1] It is established jurisprudence of the Boards of Appeal of the EPO that the priority of a previous application in respect of a claim in a European patent application in accordance with A 88 is to be acknowledged only if the skilled person can derive the subject-matter of the claim directly and unambiguously, using common general knowledge, from the previous application as a whole (see G 2/98 [headnote]).

[1.2.2] Claim 1 of the priority document of the patent in suit requires that the clay granules have a size of at least 100 mm (millimetres), whilst claim 1 of the patent in suit […] requires that such granules have a size of at least 100 μm (micrometres), i.e. a lower limit thousand times smaller than in the priority document.

It is undisputed that all the particle size values of the clay granules in the priority document are expressed in mm and that the priority document as a whole requires that the clay granules have a size of at least 100 mm and that the amount of fines, i.e. clay particles having a size below 20 mm, is limited […].

However, since the tablets of the invention have preferably a diameter between 20 and 60 mm […] and the specific tablets made of the particulate material of table 2 have a circular shape with a diameter of 54 mm […], which diameters are smaller than the clay particle size required in claim 1 and listed in table 2 and on pages 34 and 35, it would appear highly probable that the value of particle size of the clay granules in claim 1 is erroneous and that the correct particle size value should be smaller.

It thus remains to establish if it would have been immediately evident to the skilled person that nothing else was intended in claim 1 of the priority document than the correction chosen by the Respondent in the application as filed and contained in claim 1 as granted, i.e. a particle size of at least 100 μm.

[1.2.3] The priority document discloses also the size of other particulate materials different from clay. In fact, it discloses other coarse particles having a size typically above 1 mm […]; aluminosilicates with a size of 0.1 to 10 microns, i.e. 0.1 to 10 μm […]; percarbonate bleach with an average particle size from 500 to 1000 micrometers (i.e. 500 to 1000 μm) […]; flocculants having a size of at least 100 mm […]; citric acid of example B having such a particle size distribution that no more than 8% of the particles have a size greater than 1.4 mm and no more than 12% of the particles are smaller than 150 um […]; and micronised citric acid having at least 80% of particles smaller than 150 um […].

The Board thus remarks that there is not a consistent use of units of particle size in the priority document. In fact, even though the very similar values given in mm for the clay and the flocculant particle size are probably erroneous, and the units value um used for the citric acid particles does not exist in this technical field and is erroneous as agreed by both parties during oral proceedings, the other apparently correct particle size values given are expressed in μm as regards aluminosilicates and percarbonate bleach and in mm as regards citric acid and other coarse particulate material.

Therefore, since some of particle size values are expressed in mm and other in μm, it cannot be derived from the content of the priority document that the values for the clay particles should have been expressed in μm instead of in mm.

To the contrary, the passage “ … by forming the tablet from the granules of clay and other coarse particulate material, typically above 1 mm” […] seems to associate the clay particles to such other coarse particles having a size typically above 1 mm. Therefore, it appears that, in the light of this passage, at least the interpretation of the erroneous value of at least 100 mm as a value of at least 1 mm by inserting a decimal point (1.00 mm) is also equally possible as the correction chosen by the Respondent.

[1.2.4] The priority document refers to document E3 in the part of the description relating to the background of the invention. This document expresses the size of the particles constituting the matrix of the detergent tablet disclosed therein in units of μm […].

However, according to the established jurisprudence of the Boards of Appeal of the EPO the common general knowledge of a skilled person is normally represented by encyclopaedias, textbooks, dictionaries and handbooks on the subject in question or even patent specifications and scientific publications in the case that the field of research is so new that technical knowledge was not available from textbooks (see case law of the Boards of Appeal of the EPO, 5th edition 2006, I.C.1.5). Therefore, document E3, which is a patent specification published about seven years before the claimed priority date of the patent in suit, cannot be considered to represent the common general knowledge of the skilled person.

Moreover, the technical terminology used in this document is sometimes very different from that used in the priority document since in the former document particles are considered to be “fines” if their size is equal or less than 180 μm […] whilst according to the priority document “fines” are regarded to have a size of less than 20 mm […] (according to paragraph 14 of the patent in suit less than 20 μm).

Therefore, in the absence of any specific indication to this effect in the priority document, the technical information contained in document E3 cannot be considered to be also part of the invention disclosed in the priority document, which has to be understood on the basis of the technical information given in its description and the common general knowledge of the skilled person at the priority date.

Therefore, the fact that the particle sizes are expressed in μm in document E3 cannot be considered to be evidence that the clay particle sizes in the priority document had also to be expressed in μm and not in mm and that the value of claim 1 had to be understood as relating in reality to a value of at least 100 μm.

[1.2.5] According to document E20 […] it would be evident that the clay particle size in the priority document should have been expressed in μm since the particulate detergent compositions of the type referred to in the priority document are conventionally measured in units of μm and the second paragraph of page 23 refers to particulates in units of micrometers which unit is consistent with the other references to particulates throughout the priority document.

As regards the expert’s opinion contained in document E20, it cannot be considered to constitute common general knowledge for the reasons mentioned above (point [1.2.4]); moreover, it is undisputed that the particle size of particulate detergent compositions can have an upper limit above 1 mm as shown, for example, in document E3 wherein the particle size can amount up to 2000 μm, i.e. 2 mm […] and that the priority document itself refers to the particle size of coarse particulate material and citric acid by using units of mm (see point [1.2.3] above). Therefore, this opinion cannot be considered as evidence that it was common general knowledge to express the size of clay particles in detergent compositions in units of μm.

As regards the allegation in E20 […] that the second paragraph of page 23 refers to particulates in units of micrometers which unit would be consistent with the other references to particulates throughout the priority document, it has been already explained above (point [1.2.3]) that the priority documents is not consistent in the use of particle size units and that it relates to the size of other particulate materials both in units of μm and mm.

Therefore, also document E20 cannot prove that the skilled person would have understood that the clay particle size of the priority document should have been expressed in μm.

[1.2.6] The Board concludes that, on the basis of the content of the priority document and of the common general knowledge of the skilled person, it was not derivable that nothing else was intended in claim 1 of the priority document than the correction chosen by the Respondent in the application as filed and contained in claim 1 as granted, i.e. a particle size of at least 100 μm.

Since claim 1 of the patent in suit requires that the clay granules have a size of at least 100 μm, i.e. a lower limit thousand times smaller than the value of at least 100 mm required in claim 1 of the priority document, the patent in suit and its priority document refer to different inventions.

Consequently the claimed priority date of 30 April 1999 is not valid.

Should you wish to download the whole decision, just click here.