Selection Inventions and Laundry Lists

Properly protecting innovative chemical entity combinations in Europe.

A well established concept in European Patent law is the “selection invention”.

Selection inventions include inventions that claim individual elements, sub-sets or sub-ranges which have not been explicitly mentioned in a larger, known range in the prior art.

The European Patent Office Guidelines for Examination set out two well-known steps to assess whether selection inventions of a sub-range are novel over the prior art, based on established EPO Boards of Appeal decisions (T 261/15 and T279/89):

  1. the selected sub-range is narrow compared to the known range;
  2. the selected sub-range is sufficiently far removed from any specific examples disclosed in the prior art.

[A previously included and now abandoned third step to assess novelty, was a requirement to show that the selected range is not an arbitrary selection. In a relatively recent decision T230/07, the EPO Board of Appeal confirmed that the step of showing that the selected range is not an arbitrary range should only be used for assessing inventive step.]

For an example of a selection invention which claims a sub-range from a broader range, consider the following two patent applications:

A – an earlier filed patent application disclosing a new toothpaste product comprising 20-45% water and 55-80% abrasive material. There is a single example of a toothpaste having 38% water and 62% abrasive.

B – a later-filed patent application claiming a toothpaste having 23-25% water and 75-77% abrasive. The examples show that these narrower ranges increase plaque removal whilst avoiding removal of enamel, to a surprising extent compared with the single example of patent A.

Taking the two well-known steps to assess novelty, we can see that the new ranges are narrow compared to the known range and distant from the examples, and in addition, the technical effect achieved by the new ranges is not known across the ranges of Patent A. The new claimed ranges are therefore novel (and arguably inventive due to the unexpected technical effect).

The above example is a selection invention which claims a narrower sub-range of a broader range.

Selection inventions can also involve overlapping ranges. In the case of overlapping ranges, novelty is destroyed by an explicitly mentioned end-point of the known range, explicitly mentioned intermediate values or a specific example of the prior art in the overlap.

The overlap novelty problem cannot be avoided by excluding specific novelty destroying values. In relation to overlapping ranges, the question will be whether the skilled person, in the light of the technical facts and taking into account the general knowledge in the field to be expected from him, would seriously contemplate applying the technical teaching of the prior-art document in the range of overlap. If it can be fairly assumed that he would do so, then the invention is not novel.

As with any other invention, once novelty has been established for a selection invention, inventive step also has to be shown.

Ensuring a Winning Combination: Selecting from Lists in European Patent Applications

Another type of selection invention involves the selection of elements from two or more different “laundry lists” combined in a claim, when a different combination of elements from those lists is already disclosed in the prior art.

Under established case law of the EPO Boards of Appeal, any amendment to a claim has to pass three tests – novelty, essentiality and deducibility.

Novelty – the amendment should not create subject matter which is new compared to the application as filed.

Essential – removal or replacement of a feature from a claim should not remove a feature which is essential for the invention to work.

Deducible – the amendment should be directly and unambiguously disclosed in the specification as filed.

If the amendment does not pass these tests, then the claimed amendment would extend the subject matter of the application beyond what was originally filed – rendering the amended claim and the application invalid.

When making amendments by selecting elements from two or more lists, it can be very easy to fail the novelty and deducibility tests.

Under a recent decision by the EPO Enlarged Board of Appeal, G2/10, it is now clear that to overcome the three tests, an amendment in which a selection is made from two or more lists must be very clearly supported in the application as filed and that the selected combination is disclosed as having some technical advantage over other possible combinations.

In T 727/00 the board held that the combination – unsupported in the application as filed – of one item from each of only two lists of features meant that although the application might conceptually comprise the claimed  combination of items, it did not specifically disclose it in that particular individual form. For that reason alone, claim 1 of the main request was not supported by the description and contravened Art. 123(2) EPC (invalid extension of subject matter).

What does this mean in practice when selecting from lists?

Consider a scenario in which an inventor has developed a new mixture of ingredients which includes an ester. An applicant files a patent application claiming:

A composition comprising an ester formed from the reaction of a C1-C6 alcohol and a C1-C6 acid

Possible combinations of different acids and alcohols to create different esters that would fall within the scope of the claim are shown in the table below:

Alcohol Acid
Methanol Methanoic acid
Ethanol Ethanoic acid
Propanol Propanoic acid
Butanol Butanoic acid
Pentanol Pentanoic acid
Hexanol Hexanoic acid


A particularly useful subset of esters is from the reaction between a C3-C6 alcohol and any acid, and the best reaction product is formed from the reaction between butanol and ethanoic acid.

During examination, prior art is found which discloses a composition which includes propyl ethanoate.

What can the applicant do to amend its claims and overcome the prior art?

Below are some amendments proposed by the applicant and the problems the applicant will encounter in falling foul of Article 123(2), based on different scenarios of what information was specified in the application as filed.

Amendment What was disclosed in the specification as filed Amendment acceptable? Reason
Disclaim propyl ethanoate a) Only a general “ester” as defined in claim 1 No Nothing in the specification points to ethyl ethanoate being unacceptable or special in any way and it is being used in a composition in the prior art.

The disclaimer would fall foul of the “novelty” test, at least.

b) Preferred esters formed from C3-C6 alcohols No
c) the two lists listing all 6 acids and all 6 alcohols No
Restrict claim to an ester formed from butanol and any acid a) Only a general “ester” as defined in claim 1 No Unless there is a specific acknowledgement that butanol-based esters are preferred and have an advantage, picking out 6 compounds from a possible 24 or 36 from b) and c) respectively would not be considered deducible and would almost certainly fall foul of the novelty and deducibility tests.
b) Preferred esters formed from C3-C6 alcohols No
c) the two lists listing all 6 acids and all 6 alcohols No
Restrict claim to the ester being butyl ethanoate a) Only a general “ester” as defined in claim 1 No Unless butyl ethanoate is a specific example or mentioned as having an advantage over the other esters from the table combinations it will again fall foul of the novelty and deducibility tests.
b) Preferred esters formed from C3-C6 alcohols No
c) the two lists listing all 6 acids and all 6 alcohols No

In the scenarios above, the applicant doesn’t have any amendment options for each of scenarios a), b) and c). The specification should ideally have included specific mention and the advantages of butyl esters in general and butyl ethanoate in particular – which would have enabled an amendment to be made which was novel over the prior art, and which did not fall foul of the three tests for list selections.

Case law has shown that selection from even very short lists can fall foul of the novelty and deducibility tests. In T7/86 a selection from two lists, one having 5 members and other having 2 members, was deemed inadmissible. Incredibly, in a recent case, T1710/09 it would appear that even selecting a single combination of items from two lists each having only 2 members, may contravene Article 123(2) if a particular combination is not clearly and unambiguously disclosed.

Steps to avoid impossible problems with selection from lists for EPO practice

Although in practice it is difficult to predict which amendments may be needed during prosecution of a European patent application, and hind-sight analysis is not a helpful strategy, there are some practical steps you can take when drafting applications to ensure you don’t get to that “if only…” moment.

  • Ensure that your specification contains consecutive narrowing examples of your preferred ranges of components. These should ideally overlap to give maximum flexibility in amendment.
  • Don’t assume that listing every element in each list will allow you to claim the combination of any individual elements from different lists – it generally won’t unless there is a clear and unambiguous reason in the specification for your selected combination.
  • When drawing up two or more “laundry lists” of elements, ensure the specification lists sub-groups of elements of each list that are preferred, and give reasons why they are preferred.
  • If specific combinations give particular benefits that other combinations don’t have, list them separately (or group them if they have the same benefits), and explain what those benefits are.
  • Ensure that you have example embodiments of as many different combinations as possible. It is much easier to argue that a combination is not arbitrary if there is an embodiment of it described in the examples.

For further advice on selection inventions and laundry lists, please contact us to speak to one of our patent attorneys.

Wilson Gunn