7.4. Try and see situation

When neither the implementation nor the testing of an approach suggested by the prior art involves any particular technical difficulties, the consideration that the skilled person would have at least adopted a "try and see" attitude is a reason for denying inventive step (see e.g. T 333/97, T 377/95 of 24 April 2001 date: 2001-04-24, T 1045/98, T 1396/06, T 2168/11). In such situations the concept of "reasonable expectation of success" does not apply (T 91/98, T 293/07, T 688/14, T 259/15). The skilled person would prefer to verify whether the potential solution they had conceived worked, rather than abandon the project because success was not certain ("try and see" approach).

A "try and see" situation was considered to have occurred if the skilled person, in view of the teaching in the prior art, had already clearly envisaged a group of compounds or a compound and then determined by routine tests whether such compound/s had the desired effect (T 889/02, T 542/03, T 1241/03, T 1599/06, T 1364/08). See also in this chapter I.D.9.21.7. "Enhanced effect".

In T 1396/06 the board held that, in spite of the understandable uncertainties which always characterise biological experiments, the skilled person would have had no reason to adopt a sceptical attitude in the case in hand. The skilled person would have had either some expectations of success or, at worst, no particular expectations of any sort, but only a "try and see" attitude, which does not equate with an absence of a reasonable expectation of success (see also T 759/03).

In T 293/07 the board stated that the testing of humans could not be considered to represent known routine tests and accordingly the skilled person was not in a "try and see" situation. In T 847/07 the board considered it questionable whether the skilled person would adopt a "try and see" attitude at all in cases where extensive in vivo animal and ultimately human testing would be necessary in order to determine whether or not a compound has a certain property. See also T 1545/08. In T 1011/17 the board found that more extensive studies would have been required to confirm the efficacy of bosutinib in human leukemia patients with imatinib-resistant cancer cells carrying the F317L mutation. In this context, the person skilled in the art would no longer have been in a "try-and-see" situation but would have required a reasonable expectation of success as an incentive for moving to further much more extensive and larger studies in a clinical setting.

In T 62/16 the board pointed out that the skilled person assessing the possibility of starting a clinical study with a product that had never been tested on humans would have a conservative attitude. During the development of a new pharmaceutical product for use in humans there would always be the necessity, at some point, to make the step from experimentation with animal models to experimentation with humans. This step would necessarily involve some degree of uncertainty. Whether or not the skilled person would decide to start a clinical study with the product in question was a matter that had to be decided in the circumstances of each case.

In T 259/15 the board held that the case law did not support the conclusion that the skilled person would systematically avoid a "try-and-see" approach whenever testing on human patients was involved, regardless of the circumstances of the case. In the circumstances of the case in hand, the board considered that the skilled person would test the device in question (a buprenorphine transdermal patch) on human subjects despite the uncertainties as to the maximum duration of application.

In the light of the closest prior art the board saw the technical problem to be solved in T 886/91 in the exact identification and characterisation of DNA sequences of HVB genome subtype adyw. The board pointed out that the situation in T 886/91 could not be compared with the one in T 223/92 and T 500/91, where production of a partially known protein in a recombinant-DNA system was achieved and considered inventive on the basis of the fact that, in the specific circumstances of those cases, there was no realistic expectation of success. In the case in point the closest prior art had already disclosed the cloning and expression of the HBV genome subtype adyw. The identification and characterisation of the claimed specific sequences of the same genome involved for the skilled person nothing more than the performance of experimental work by routine means in connection with the normal practice of filling gaps in knowledge by the application of existing knowledge.

In T 688/14 appellant I argued that the skilled person would have adopted a sceptical attitude and not a "try and see" attitude. The board disagreed. Document 8 not only informed the skilled person of the presence of several problems when trying the method in question but it also provided means and measures to overcome them. Indeed, these problems were already known in the art and means and measures to solve them were also provided there. There was no reason for a person skilled in the art to ignore all the information to hand and select the worst possible known system or method when facing a "try and see" situation. The board held that it was worth noting that, in the case in hand, the skilled person was not looking for an improvement or a surprisingly advantageous effect, but only for an alternative method.

In T 1715/15 the board found that the person skilled in the art could be both regarded as being cautious and of a conservative attitude (see I.D.8.1.3) but also tasked with the furthering of the prior art by routine adaptations or trials (see also T 688/14, T 2697/16 and T 1289/22).

In T 2015/20 the board was of the opinion that the defined subject-matter of claim 1 was not the obvious result of routine experimentation, but rather represented the unexpected outcome of a study for finding an aclidinium dose for treatment of a chronic disease which combined optimised effectiveness with the absence of side-effects. The board thus concluded that the subject-matter of claim 1 involved an inventive step. See also chapter I.D.10.8 "Unexpected bonus effect".

In T 3016/18 the board said that a skilled person could theoretically replace a given layer of a layered composite with any randomly chosen alternative layer. However, they would only consider this as a "try and see" option within the context of their usual routine approach if the possible alternative layers were known to provide the desired functionality of the layer to be replaced. This condition was however not met in the case in question.

In T 2695/18 the board disagreed that the skilled person combining the teaching of document D1 with either D3 or D17 was at least in a "try-and-see" situation, such that the skilled person would inevitably have arrived at the claimed subject-matter. There was no pointer in any of the available documents; none of the prior art teachings clearly envisaged a way of proceeding in the light of the problem to be solved; the skilled person was not in the position to verify prior art teachings by routine methods because Mn**(2+)'s dose effect on increasing sialylation was not known and therefore this one way among the many possible ways of solving the problem was not foreshadowed.

In T 2565/19 the board stated that in the case in hand the importance of research on humans in a medical context would have led the skilled person to repeat the experiments done in rats in document D2 in humans, even in the face of alternative explanations for the results and even in the face of the knowledge that only one type of TRH receptor had been found in humans. The board accepted it was common knowledge in the art that working with post-mortem human tissue and brain tissue in particular was associated with particular practical problems. However, given that the skilled person was seeking to replicate an animal model in humans, they had no choice but to turn to human tissue.

Decisions T 455/91 (OJ 1995, 684), T 412/93, T 915/93, T 63/94, T 856/94, T 91/98, T 111/00 and T 948/01 also consider this topic.