LEO'S patent not "obvious to try" because there was "no reasonably optimistic expectation" of success regarding the claimed invention

16 minute read
03 August 2015


The Court of Appeal has overturned Birss J's decision in Teva v LEO and ruled that LEO's patents regarding its Dovobet ointment for psoriasis are valid.

In doing so, Sir Robin Jacob has provided useful guidance on the "obvious to try" doctrine, the relationship between real persons skilled in the art and the hypothetical skilled addressee, and the importance of considering the wider context in which the invention was made.


LEO's patents concerned a combination of two active ingredients (calcipotriol (a vitamin D analogue) and betamethasone (a corticosteroid)) in a non-aqueous solvent (Arlamol E).

At first instance, Birss J adopted an unusual approach to the assessment of Teva's obviousness challenge, as discussed in our earlier alert on the case. It involved:

  • the skilled addressee starting from the common general knowledge (which included a need for a non-aqueous topical medicament containing calcipotriol and betamethasone);
  • the skilled addressee being presented with a piece of prior art ("Turi") which disclosed Arlamol E's use as a solvent for a corticosteroid alone; and
  • the skilled addressee deciding to include it in his list for further investigation.

Birss J found as a matter of fact that Arlamol E was not a usual solvent which a formulator would try to use. (In fact he held that it was not common general knowledge, and that Turi would not have been found in a literature search). Despite this, in view of Turi, "there was a sufficient prospect of a positive result in the tests with this compound to make it worth testing". Upon carrying out the "entirely routine" screening he would find that Arlamol E was in fact a good solvent to use in the combination. Consequently, ruled Birss J, the 'invention' was obvious to try and the patent was invalid.

Birss J had erred in principle

In a decision dated 28 July 2015 (2015] EWCACiv 779), the Court of Appeal disagreed with Birss J's analysis.

Birss J's principal error was in failing to attribute the necessary standard of expectation when applying the "obvious to try" test. Contributing to this was Birss J's additional failure, in Sir Robin Jacob's view, to impute to the notional skilled addressee "the real prejudices and practices of persons skilled in the art" about using Arlamol E as the solvent, his failure to recognise the importance of certain findings of fact which did not support a conclusion of obviousness, and his failure to consider the wider circumstances of a long-felt and unmet want preceding the "significant advance" (and "advance in human knowledge") represented by the invention.

The "obvious to try" standard

As we noted in our report on the first instance judgment in this case (link above) regarding the "obvious to try" doctrine, Birss J had stated:

"It is wrong to ask whether something might achieve a particular desired effect. It is correct to ask whether it was obvious that it would achieve that effect".

While this statement appears to be correct, Birss J had apparently proceeded to answer the first (i.e. the "wrong") question, not the second one.

Sir Robin Jacob pointed to other passages of Birss J's judgment as revealing the error, including extracts from the following:

  • "[t]he skilled formulator would carry out compatibility tests on a number of possible solvents. The number would be about 10 to 20" (paragraph 72),
  • "[t]he notional skilled formulator would test some familiar compounds but .... would not be put off from including unfamiliar compounds merely because of their unfamiliarity" (paragraph 79), and
  • the disclosure of Turi "would be sufficient grounds to include [Arlamol E] in pre-formulation tests. Based on what the skilled formulator knew about it at the time there was a sufficient prospect of a positive result in the tests with [Arlamol E] to make it worth testing. It was obvious to do so" (paragraph 92).

However, Sir Robin Jacob said that the inclusion of a specific solvent in a list of solvents to be tried is not sufficient to render the claimed invention (which covered only that one solvent) obvious. Quoting from his own judgment in St-Gobain v Fusion Provida he said:

"Mere possible inclusion of something within a research programme on the basis you will find out more and something might turn up is not enough. If it were otherwise there would be few inventions which were patentable. The only research which would be worthwhile (because of the prospect of protection) would be in areas totally devoid of prospect".

This was so even though the field in the present dispute was empirical, such testing "was entirely routine" and once tested, Arlamol E was found to work.

In order to render the invention invalid, Arlamol E itself had to be obvious to try - and the prospect of success had to raise it over and above other candidates. A finding that it was obvious to include Arlamol E in his list of solvents to try, and that trying it would in fact have led to success, was not enough: the later finding did not alter the expectation of success regarding Arlamol E before conducting the test. As Sir Robin Jacob said: "well-worth investigating" is not the same as "a fair expectation of success".

The findings of fact did not permit a finding of obviousness

Sir Robin Jacob explained further, that the judge had missed the real significance of the evidence and of his own findings of fact. The judge had accepted evidence that to the skilled person, identifying a non-aqueous solvent which would actually work to produce a stable ointment was not easy. Sir Robin Jacob said:

"The Judge said that Arlamol E had the desired characteristics and so there were 'sufficient grounds to include the compound in pre-formulation tests'. I do not see that follows. Many non-aqueous solvents may have had the desired characteristics - propylene glycol is a particularly good instance. But there was nothing disclosed about Arlamol E that made it anything like an outstanding candidate - any different from any other non-aqueous solvent.

"The Judge said that 'there was a sufficient prospect of a positive result in the tests with this compound to make it worth testing.' But that is to say no more than that there was a sufficient prospect of success with any non-aqueous solvent. On this analysis all such solvents were worth testing. Yet the evidence had shown that the 'apparent pH' problem was real and that one could not say that just because a solvent was non-aqueous it would work."

Sir Robin Jacob said that he was confirmed in his view that the patent was not obvious by a further consideration. He noted that Birss J had "dated all his findings about common general knowledge as at the priority date, April 1999", but that in fact all those facts had been common general knowledge since at least 1995, and yet "no-one found a way to put the actives together in an ointment (with any non-aqueous solvent, not just Arlamol E) until LEO did it with the invention in the patents". Despite the long-felt want and the advance represented by LEO's solution, there was "no explanation of why that solution was not done before when it could have been".

As the final nail in the coffin for Teva, the Opposition Division of the European Patent Office (EPO) had, after Birss J's first instance judgment (with which it was provided), declined to follow the judge's reasoning and rejected Teva's opposition. Sir Robin Jacob was "not surprised".

The skilled addressee of the patent

Behind the judge's conclusion on obviousness lay also his assessment of the skilled addressee of the patent and his or her common general knowledge.

Sir Robin Jacob observed as "rather odd" the judge's suggestion that the notional person skilled in the art would be different from the real skilled person.

Birss J had said: "The skilled formulator would decide what compounds to test based on the properties of the compounds. LEO emphasised Professor Brown's evidence that familiarity with such compounds would be a critical element in the skilled formulator's thinking. I accept that familiarity would always play a part in the choices made by real formulators working in real organisations since it maximises the chances of success by using tried and tested compounds which are often found to work. However I find that the notional skilled formulator would not be as conservative in his or her thinking as that evidence might suggest..."

Sir Robin Jacob did not like this. He said: "But the law of obviousness attributes to the notional person the real prejudices and practices of persons skilled in the art. For instance the "bagridden" mindset of real vacuum cleaner designers was attributed to the person skilled in the art in Dyson v Hoover [2002] R.P.C. 22. "

This is a reminder worth heeding.

It may perhaps be queried whether Birss J's comment was merely an expression of disagreement with LEO's expert as to the mind-set of the real (and hence the notional) skilled addressee. However in view of Sir Robin Jacob's other conclusions (discussed above) the point is probably moot.

The Pozzoli approach

As we noted in our report on the first instance judgment in this case (link above), Birss J's approach to obviousness appeared to start with the traditional UK Pozzoli approach, but then (at stage 3, which requires identification of the difference between the pleaded prior art and the invention) to depart from that and to morph into more of a "problem-solution" approach.

Sir Robin Jacob did not criticise Birss J's choice not to adopt the whole Pozzoli approach (or the whole problem-solution approach). He did however note at the outset to his judgment that both were "often a helpful way of approaching the problem" of obviousness. Further, towards the end of his analysis, he did perhaps hint that a full application of either the Pozzoli or the problem-solution approach might have assisted in the present case. At paragraph 33 he said:

"Putting this point into a Pozzoli structured analysis, the difference between the prior art (Turi) and the invention was that Turi was a mono active product using Arlamol E. The invention is a double active product. Turi would be seen as using one of a large number of possible non-aqueous solvents. It might provide stability for the two actives, just as any of the others might. But there was no reasonably optimistic expectation that it would. Finding that it really did was an invention and an advance in human knowledge".

At paragraph 39 Sir Robin Jacob recorded the conclusions of the EPO Opposition Division's problem-solution analysis (which requires an assessment of the closest prior art) and in doing so, emphasised particularly the final point as follows:

"In [Turi] the problem was neither mentioned nor even suggested and considering [Turi] as the closest prior art is merely the result of an ex-post facto analysis" (emphasis added by Sir Robin Jacob).

In our report on the first instance judgment in this case, we raised the questions as to whether a proper application of either of these approaches in full would have resulted in Birss J coming to a different decision on obviousness. Bearing in mind his conclusion on the facts and their relative importance it may not ultimately have made a difference. However, the guidance given by the Court of Appeal in this judgment seems to suggest that closer adherence to established assessments of obviousness is preferable.


This is a very important judgment of the Court of Appeal, particularly for the pharmaceutical industry and all industries where empirical research forms the heart of the industry and forms the basis for many important advances in the art - and indeed in human knowledge. The first instance judgment in this case conjured up strong echoes from a past era - in which having a UK patent upheld as inventive in an empirical art was the exception to the rule.

With fifteen uses of the word "real" - whether to describe real problems, real organisations, real prejudices, real formulators, real world and ultimately a "real advance" - this Court of Appeal judgment is firmly based in, and recognises the importance of, reality when assessing the validity of an invention.

Overall, the Court of Appeal's decision is therefore a positive re-affirmation that the "obvious to try" doctrine does not mean "obvious to include in an empirical research project". Rather, a patent's claim will only lack inventive step if it was obvious to try what is claimed with a reasonable prospect of success. This builds upon the guidance from Kitchin J in Generics v Lundbeck [2007] RPC 32 at [72]:

"The question of obviousness must be considered on the facts of each case. The court must consider the weight to be attached to any particular factor in the light of all the relevant circumstances. These may include such matters as the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort involved in pursuing them and the expectation of success."

And also upon the guidance of Lord Hoffmann in Conor v Angiotech [2007] RPC 32 at [42]:

"[T]he notion of something being obvious to try was useful only in a case in which there was a fair expectation of success. How much of an expectation would be needed depended upon the particular facts of the case".

Sir Robin Jacob's judgment confirms that in an empirical field, despite the conduct of a broad test perhaps being an obvious and routine step to take, a patent will only be obvious if at the priority date there was a reasonably optimistic expectation that the particular claimed invention would work.

Finally, it is useful to see another citation of Jacob LJ's (as he was then) statement on the requisite degree of expectation of success, from the Court of Appeal in St Gobain, to remind ourselves that invention can of course lie in areas other than those " totally devoid of prospect". The sentence that Sir Robin Jacob left off that quote in his re-statement this time was that: "The "obvious to try" test really only works where it is more-or-less self-evident that what is being tested ought to work."

That (perhaps) extreme level of "expectation" was subsequently tempered slightly in Kitchin LJ's judgment in Novartis v Generics (2012 EWCA Civ 1623) in which he said: "What is a reasonable or fair expectation of success will again depend upon all the circumstances and will vary from case to case. Sometimes, as in Saint Gobain, it may be appropriate to consider whether it is more or less self-evident that what is being tested ought to work. So, as this court explained in that case, simply including something in a research project in the hope that something might turn up is unlikely to be enough. But I reject the submission that the court can only make a finding of obviousness where it is manifest that a test ought to work. That would be to impose a straightjacket upon the assessment of obviousness which is not warranted by the statutory test and would, for example, preclude a finding of obviousness in a case where the results of an entirely routine test are unpredictable."

However, where (as in this case) there are numerous potential avenues empirically to pursue, the "more-or-less self-evident" level of expectation may well be justified - to raise the particular solution out of the morass of background noise - before one can say it was "obvious".

Let's "keep it real".

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