T 0694/15 - The terminology "closest prior art" is somewhat misleading

Key points

• This is an examination appeal about inventive step.
• “The Examining Division started from document D8. The Board also considered documents D9 and D5 as possible starting points. The [applicant] disagreed that D5 was the closest prior art”
• The Board: “the terminology "closest prior art" is somewhat misleading. It is perhaps preferable to use the terminology "starting point (in the prior art)". It can be economical to start from prior art that is in some sense close to the invention, in the hope that the consideration of this single starting point will be enough to establish whether the claimed subject matter would have been obvious.”
• “However, if this fails, before arriving at the conclusion that the subject matter would not have been obvious, it is necessary to consider other possible starting points, to see whether there are any other paths leading to the invention, that the skilled person would have taken when searching for solutions to technical problems pertinent to that starting point. If such a path exists, then the invention would have been obvious.”
• “It has to be noted, however, that a problem which is not apparent from the context of the starting point, but which is derived only with knowledge of the invention, is very likely to be the result of hindsight.”
• The Boards finds the claims to be inventive.

EPO  T 0694/15 - link




9. The Examining Division started from document D8. The Board also considered documents D9 and D5 as possible starting points.

10. The appellant disagreed that D5 was the closest prior art, because it only provided, as a visual indication, the switching on or off of an LED, and did not provide for a measurement of a level in the sense of the claim, whereas D9 did.

11. This argument fails in view of the Board's claim construction (point 8, above). But the argument is actually of no relevance to the question of whether D5 can be selected as closest prior art.

12. Having one less feature in common with the claim may mean that it appears less likely that the skilled person would arrive in an obvious manner at something falling within the scope of the claim, but it does not mean that the skilled person could not have arrived at such subject manner without hindsight, possibly while looking for a solution to a different objective technical problem.

13. As this Board, in a different composition, has already said (T 405/14 Self-testing sensor / William L. Smith), the terminology "closest prior art" is somewhat misleading. It is perhaps preferable to use the terminology "starting point (in the prior art)". It can be economical to start from prior art that is in some sense close to the invention, in the hope that the consideration of this single starting point will be enough to establish whether the claimed subject matter would have been obvious. However, if this fails, before arriving at the conclusion that the subject matter would not have been obvious, it is necessary to consider other possible starting points, to see whether there are any other paths leading to the invention, that the skilled person would have taken when searching for solutions to technical problems pertinent to that starting point. If such a path exists, then the invention would have been obvious. What is decisive for establishing obviousness is not the closeness of the starting point but the overall likelihood of the path, given the starting point.

14. Some prior art documents may be easily discarded, but this cannot be done merely because there is another "closer" document. It has to be done on the basis of an evaluation of the likelihood of the existence of an obvious path to the claimed subject matter.

In so doing, it may indeed be possible to conclude, for example because the situation is analogous, that starting points that remain to be considered are no more promising that those that already have been considered, and their evaluation can be halted.

15. It is further necessary to investigate all technical problems that could lead to subject matter falling within the scope of the claim. There may be more than one objective technical problem, either because one can ascribe distinct effects to the same differentiating features, in which case it might be possible to consider problems based on any one of them, or because the differentiating features comprise alternatives (or subranges within a broader range) with different associated technical effects. The latter is the case here, as it will be discussed below.

16. It has to be noted, however, that a problem which is not apparent from the context of the starting point, but which is derived only with knowledge of the invention, is very likely to be the result of hindsight.