Thursday, 4 August 2011

T 53/08 – The Closer

This is an appeal against the decision of the Opposition Division revoking the opposed patent. It contains some interesting paragraphs on the determination of the closest prior art.

Claim 1 before the Board read (in English translation):
1. A herbicide/safener combination, which comprises
A) as herbicidally active compound a compound of the formula (A1)

or a salt thereof, and

B) one or more safeners
a) from the group of the compounds of the formulae (B1)

in which
X is hydrogen, halogen, (C1 -C4)alkyl, (C1 -C4)alkoxy, nitro or (C1 -C4)haloalkyl,
Z is OR1, SR1 or NR1R2 or is a saturated or unsaturated 3- to 7-membered heterocycle having at least one nitrogen atom and up to 3 hetero atoms which is linked to the carbonyl group in (B1) via the nitrogen atom and which is unsubstituted or substituted by radicals from the group consisting of (C1 -C4)alkyl, (C1 -C4)alkoxy or substituted phenyl,
R1 is hydrogen or an unsubstituted or substituted aliphatic hydrocarbon radical,
R2 is hydrogen, (C1 -C6)alkyl, (C1 -C6)alkoxy or substituted phenyl,
n is an integer from 1 to 5,
W is a divalent heterocyclic radical from the group of the partially unsaturated or heteroaromatic five-membered heterocycles having 1 to 3 hetero ring atoms of the type N and O, wherein one oxygen atom and at least one nitrogen atom are present in the ring.

*** Translation of the German original ***

[3] When applying the problem-solution approach, it is necessary to first determine the closest prior art.

[3.1] Documents D1 and D10 – as well as the impugned patent - concern herbicides which are used on weeds in corn, rice and cereal cultures […].

[3.1.1] Document D1 discloses the herbicide of formula (A1)

and its combination with other active substances […]. The subject-matter of D1 differs from the subject-matter of the claims of the impugned patent only in that the combinations of D1 do not comprise a compound of the formula (B1):

[3.1.2] Document D10 discloses compositions containing substituted isoxazoline derivatives, wherein the isoxazoline derivatives act as safeners. The generic formula of the isoxazoline derivatives overlaps with the generic formula of compounds (B1) of the impugned patent. In particular, the safeners (B1-9) and (B1-11) that are preferred according to the impugned patent […] are also described in document D10 […]. It is true that document D10 discloses that pyridylsulfonylurea-type herbicides can be combined with safeners of formula (B1) […] but it does not disclose the specific pyridylsulfonylurea derivative (A1) as defined in the claims of the impugned patent, wherein the pyrimidinyl and the pyridinyl rings can be substituted by alkoxy groups and a haloalkyl group, respectively. […] Therefore, the subject-matter of document D10 differs from the subject-matter of the claims of the impugned patent.

[3.2] The disclosure of each of the two documents differs from the impugned patent by one single feature only. When assessing which of documents D1 or D10 is to be considered as the closest prior art, the following is to be taken into account:

It is apparent from the impugned patent […] and the application as originally filed […] that the selectivity of highly active herbicide substances is often insufficient. Moreover, the application of small amounts of these active substances does not lead to the elimination of the undesirable weeds without harming the useful plants (Kulturpflanzen). Therefore, the objective of the patent was to further develop the highly active substance of formula (A1) in such a way that it does not harm useful plants in a significant way when used in herbicidally active concentrations. Therefore, the natural starting point for the invention is the document which discloses the the active substance of formula (A1), i.e. document D1 (see T 487/95 [6.1-2]) Although suggestions on how to solve the problem can be found in document D10, this document primarily concerns the development of isoxazoline derivatives as safeners and, therefore, prima facie the skilled person would not consider this document as starting point for improving the selectivity of a specific herbicide.

[3.3] Thus document D1 is the closest prior art.


[3.4] Starting from document D1, the problem to be solved can be seen in providing herbicidal compositions having an improved tolerability (selectivity) for the useful plants.

[3.5] From comparative data D12 and D13 it follows that the harmful effects of compound (A1) is reduced when a safener is added. Document D12 proves that the damage in corn is reduced by 75 to 25% when the safener (B1-9) is added […]. Document D13 shows that the selectivity in wheat of the Rektor type, barley of the Baronesse and Duet types and wheat of the Triso type is increased when these plants were treated with compounds according to the invention […]. Therefore, the problem mentioned under [3.4] was indeed solved.


[3.6] When starting from document D1 and looking for a solution to the problem mentioned under [3.4], the skilled person would come across document D10, which also deals with the selectivity of herbicides with respect to cereals, rice and corn […] As mentioned above (see point [3.1.2]), document D10 discloses isoxazoline derivatives as safeners, which overlap with the generic formula of the (B1)-compounds of the impugned patent, and in particular the two specific safeners (B1-9) and (B1-11), which are also mentioned in the impugned patent. Moreover, the generic description of the pyridylsulfonylurea derivatives comprises specific compound (A1) […]. Therefore, the skilled person would expect that the selectivity of compound (A1) according to D1 is increased when a safener according to document D10 is added. Therefore, the skilled person would arrive at the compounds according to the invention without exercising any inventive activity (see T 288/98 [2.10]).

[3.7] In its trials D12 and D13 the [patent proprietor] has also shown that the safener (B1-9) displays a higher activity when the pyridylsulfonylurea derivative H.2 tested in document D10 is replaced by the (A1) compound according to the impugned patent. The Board agrees with the [patent proprietor] that in view of those experimental results, one could come to the conclusion that the subject-matter of the present claims involves an inventive step if document D10 was considered to e the closest prior art.

However, according to the established case law of the Boards of appeal, when there is more than one document that could be considered to be the closest prior art, then the document from which the skilled person would arrive at the subject-matter of the invention most easily has to be considered to be the closest prior art (see T 824/05 [6.2]).

In the present case, this is document D1 […]. For this reason, the Board cannot follow the arguments of the [patent proprietor] in respect of inventive step of the main request.

[3.8] Therefore, the subject-matter of the main request does not involve an inventive step (A 56).

Finally, the appeal was dismissed.

To download the whole decision (in German), click here.

The file wrapper can be found here.


pat-agoni-a said...

Often a patent proprietor argues in defence of his patent that a paricular document be considered the closest prior art instead of the one chosen by the opponent, since starting from this document the invention would involve an inventive step. However, it is the opponent who determines the line of attack and it is the proprietor who has to defend himself against the attack chosen by the opponent. Arguing that another line of attack would be less effective is at least candid.

This reminds me of a castle under siege in which the owner suggests to the attacker to attack the south side, since that side is better defended. ;-)

I believe few boards would follow that suggestion.

Something very different however is the argument that the document chosen by the opponent is not a valid starting point. The boards often have stressed that it is not the number of common features, but a common aim, which determines a valid starting point. Given several valid starting points (also called closest prior art documents) the proprietor has to defend himself against all of them.