T 1730/09 – Essentially

Both the patent proprietor and the opponent filed an appeal against the decision of the Opposition Division to maintain the patent in amended form.

Claim 1 of the main request before the Board read :

A viscoelastic fluid consisting essentially of:

(1) an aqueous medium;

(2) a surfactant represented by the formula (I):

wherein R1 is RCONHCH2CH2CH2(-) wherein R is an alkyl group containing from 14 to 24 carbon atoms, which may be branched or straight chained and which may be saturated or unsaturated,

R2 and R3 are each methyl;

R4 is a hydrocarbyl radical with a chain length of 1 to 4; and

(3) a member selected from the group consisting of organic acids, inorganic salts, and combinations of one or more organic acids with one or more inorganic salts;

wherein said fluid exhibits the property of viscoelasticity. (my emphasis)

Among other things, the opponent pointed out that in the absence of a definition in the patent in suit of the term “essentially”, the wording “consisting essentially of” would not identify precisely the amounts of components which could be contained in the claimed composition in addition to those explicitly listed; reference was made in this respect to decision T 728/98.

The patent proprietor responded that it was clear that the wording “consisting essentially of” allowed only the presence of impurities in addition to the specifically listed components.

What did the Board decide ?

[1.2.3] As regards the wording “consisting essentially of”, which is also part of claim 1, it was not contained in any of the granted claims. Therefore, the alleged lack of clarity of this term raised by [the opponent] can be objected in opposition appeal proceedings.

However, as reported in the Case Law of the Boards of Appeal of the EPO, 6th edition (2010), II.B.5.2, referring to decisions T 759/91 and T 522/91, the wording “consisting essentially of”, at variance with the wording “comprising substantially”, has a defined meaning because of the unequivocal character of the words “consisting of”; therefore, the use of the unequivocal words “consisting of” in combination with “essentially” has been found to solve all interpretation problems of the unclear claims examined in such previous cases.

The cited decisions T 759/91 [2.2] and T 522/91 [2.2] both refer to the decision T 472/88 [3], wherein it was decided that the term “consisting essentially of” was clear and allowed the presence of other components in a claimed composition in addition to the components mandatory in the claim, provided that the essential characteristics of the claimed composition are not materially affected by their presence.

The Board agrees with these previous decisions. Therefore, even though the word “essentially” does not identify precisely the amounts of additional components which could still be contained in the claimed viscoelastic fluid, the wording “consisting essentially of” allows in the present case that the composition of claim 1, which must be viscoelastic, consists of the mandatory components listed in the claims and can contain additionally only other components which do not materially affect the essential viscoelastic characteristics of the composition, e.g. minor amounts of impurities as submitted by [the patent proprietor] during oral proceedings.

[1.2.4] The decision T 728/98, cited by [the opponent], concerns the clarity of the different wordings “substantially pure” or “substantially free of” (point [3] of the reasons), which do not contain the word “essentially”; therefore, this decision concerns a legal situation which is more similar to that of the previously cited decisions T 759/91 and T 522/91, wherein the wording “consisting substantially of” was found not to be clear. Consequently, this decision concerns a different legal situation and is not applicable to the present case.

The Board concludes that the wording “consisting essentially of” contained in claim 1 of auxiliary request 8 complies with the requirements of clarity of A 84 EPC 1973.

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