EP Case Law in Brief: Long-felt want and inventive step

“Where the invention solves a technical problem which workers in the art have been attempting to solve for a long time, or otherwise fulfils a long-felt need, this may be regarded as an indication of inventive step.”

The EPO Guidelines (G-VII, 10.3) describe the basic approach to the concept of long-felt want or long-felt need – terms that are used interchangeably. Long-felt want is an example of a secondary indicator of inventive step. Secondary indicators are factors which, although on their own may not be enough to indicate an inventive step, may be supportive of inventive step along with other arguments and depending on the specific context. Other examples of secondary indicators include commercial success and bonus effect. Our previous edition of EP Case Law in Brief, published here, focussed on commercial success, and we now review the case law relating to long-felt want.

The topic of satisfaction of a long-felt want is dealt with in section I.D. 10.4 of the Case Law of the Boards of Appeal, and the related topic of age of documents is dealt with in section I.D. 10.3. The basic principle, as laid down in T 109/82, is “the fact that the state of the art has been inactive over a long period prior to the invention may be an indication that an inventive step is involved if during that time an urgent need for improvement has demonstrably existed”. T 109/82 was concerned with claims directed to a device for measuring, testing and – in particular – setting the maximum sound-pressure output of a hearing aid. The patentee argued, inter alia, that “despite the [prior art] cumbersome sound-measuring box having been in use for decades with all its shortcomings, no person skilled in the art [had] ever hit on the idea of doing without it” to simplify that measuring process, for example by dispensing with the box (section 5.5 of the Reasons). However, the Board held that “the time factor cannot be the sole yardstick” and that non-obviousness must be “supported by other concurrent factors”, such as “an urgent need which has not been met over a long period of time”. Therefore, “in view of the fact that the state of the art [had] clearly been inactive over a long period and the absence of indications in the entire prior art as disclosed of attempts or efforts to omit the measuring box, the Board [concluded] that such a need [did] not exist, particularly since the appellant [had] failed to provide evidence to the contrary”.

The concept of a long-felt need was defined further in T 605/91 where it was said to not be sufficient for one skilled person to discover the need. Instead, ‘various and repeated attempts’ to deal with the relevant disadvantages are required for a long-felt need to support an inventive step.

It is not – however – all bad news for patentees. In T 271/84, the Board found that “if a process has been performed successfully on a commercial scale for more than 20 years in spite of economic disadvantages associated with it, and the claimed invention provides a solution to the technical problem of avoiding such economic disadvantages, this supports a finding of inventive step” (Headnote). It is clear therefore, that despite the challenges, arguments surrounding a long-felt want can be persuasive. In T 271/84, the patent claims were directed to the purification of gas, in particular with the removal of sulphurous contaminants. “The technical problem in respect of the closest art was to improve the economy of the process by reducing the material and energy requirements corresponding to the use of large quantities of absorbent” (section 6 of the Reasons). The claimed solution involved removing the sulphurous contaminants using a different process, which would not have been obvious starting from the closest prior art, namely the commercially successful Rectisol process. Notably, the Board considered that the opponents “were in full possession of all relevant state of the art knowledge for some years before the priority date of the European patent, and did not think of advancing from their [commercial] Rectisol process to the claimed process in the way that they now allege to be obvious”.

The concept of long-felt need is also linked to the age of prior art documents. As described in T79/82 and T295/94, ‘the age of documents known long before the filing date might only be an indication of an inventive step if a need for the solution of an unsolved problem had existed for the entire period between the date of the documents and that of the invention.’ Importantly, this time period is not the period between the publication of a document and the filing date, but the period between the problem becoming apparent and the filing date of the application which provides the solution, as laid out in T 478/91 and applied in T 6/02.

There are a number of Board of Appeal cases, where the age of documents was considered to support an inventive step. These cases relate to different ages, such as 70 years (T 986/92), 60 years (T 626/96 and T 833/99), 50 years (T 774/96), 23 years (T 273/92, where the invention related to ‘an economically important and heavily worked field’ was important), 16 years (T 540/92) and even 11 years (T 203/93 and T 795/93, where the invention related to ‘a technical field wherein intensive development efforts were made’ and T 697/94).

In T 330/92, the Board found that documents reflecting the common general knowledge had been known for at least 17 before the filing date. The Board held that ‘the professional world has been “blind” to this knowledge over this long period of time’ and therefore considered this to be a ‘strong indication of the inventive step of the solution according to claim 1’.

In T 1077/92, both the problem and its solution had co-existed for 100 years, and yet the question remained as to why the seemingly obvious step had not been taken. The Board said they could ‘find no answer to that question, other than to conclude that, for whatever the reason, it cannot have been obvious. If the step had been an obvious one, it would have been taken long ago… in the Board’s judgement it must have required inventive insight to perceive that the principle of self-regulation of concentration could advantageously be applied to solve the problem.’

The above concept is not just limited to extreme cases such as where the problem was known for 100 years. In T617/91, the Board noted that in fields ‘where active research continues on a worldwide scale, seven years is a relatively long time.’ They acknowledged that ‘100 years in that earlier case is a more extreme situation than the 7 years in the present case’, but nevertheless stated that ‘the fact remains that throughout that time interval there was a strong incentive amongst SG iron makers throughout the world to look for better methods which would be more safe, and more economic’. The Board therefore concluded that ‘although document (1) seen in hindsight might seem to suggest a solution, the Board draws the inference that the generality of its teaching was such that it remained unnoticed, and would have remained so but for the inventive insight of the Appellant.’

In T 1192/09, the closest prior art (D8) was published about 12 years before the filing date. The inventors of D8 – after the filing date of the contested patent – filed a later application directed to the same invention as claimed in the contested patent, which was granted (D10). The Board considered the fact that it took the inventors of D8 12 years to file D10 as an indication of an inventive step. The Board stated:

“The facts that the very inventors of D8 did not propose the claimed structure, with its uncontested advantages, until 12 years after the publication of D8, and that this structure was later praised in D10 and made the subject of a granted European patent is considered by the board as an additional indication of the non-obviousness of the concept which forms the basis of the claimed invention.”

Although many of the above examples show where the age of documents leads to a successful finding of inventive step for the patentee, this is not universal. In T 123/97, it was argued that more than 20 years had elapsed between publication of two prior art documents and the filing date. However, the Board held that ‘the failure to adopt an obvious solution to the technical problem underlying the patent in suit may result from a variety of causes: for example as stated by the appellant, there may have been a commercial reason for not adopting this new technique.’ Therefore, the Board did not consider there to be an inventive step.

The link between age of documents and long-felt want can be seen in T1014/92, where the appellant argued that because two documents had been available to the public for about 35 years without being combined, this was evidence that there was no obvious connection between the documents. However, the Board found that this ‘conclusion might only have been drawn if evidence relating to time were corroborated by other evidence, such as long-felt want’.

In summary therefore, the closely related topics of long-felt want/need and age of documents can – in the right circumstances – be powerful tools for patentees to argue for an inventive step. As secondary indications, they will not be sufficient on their own, but can help bolster other inventive step arguments.