Obviousness in England – Has the pendulum started to move?

On 18 November 2005 the English High Court (Christopher Floyd QC sitting as a Deputy Judge of the Patents Court) handed down its judgment in the case of Schering Plough v Norbrook Laboratories. The Court’s interpretation of the recent decision of the Court of Appeal in St Gobain v Fusion Provida suggests that the Patents Court’s attitude towards obviousness may be shifting in favour of the patentee. Following St Gobain the Court applied the test that the claimed invention was only ‘obvious to try’ where it was more-or-less self-evident that what is being tested ought to work. This indication that an ‘expectation of success’ has been re-introduced into the English law of obviousness should encourage patent holders.


Norbrook Laboratories (Norbrook), the Irish pharmaceutical company, owns a European patent relating to a veterinary product comprising two medicaments, a long-acting antimicrobial and an anti-inflammatory drug, for the treatment of a range of infectious diseases in animals, including bovine respiratory disease. Schering-Plough (S-P) applied to revoke Norbrook’s patent alleging that it is both obvious in light of the common general knowledge and cited prior art and insufficient.


It was well known at the priority date to treat bovine respiratory disease concurrently with a long-acting antimicrobial drug and an anti-inflammatory (typically of the non-steroidal type). In addition at the priority date S-P marketed a combination product comprising a short acting formulation of an antimicrobial drug (oxytetracycline) and a non-steroidal anti-inflammatory (flunixin). According to the patent the object of the invention was to provide a “long-acting or single treatment formulation which has both antimicrobial and anti-inflammatory effect”. As well as providing a convenience benefit over existing treatment regimes the patent included data to show the advantages of a combination of long-acting oxytetracycline and flunixin over treatment with either drug alone.


S-P claimed that the patent was invalid for obviousness in light of both common general knowledge, principally S-P’s own pre-priority date short-acting combination product, and prior art publications reporting on the treatment of cattle with S-P’s combination product and concurrent therapy with a long-acting antimicrobial drug and an anti-inflammatory.
Following the structured approach to obviousness approved by the Court of Appeal in Windsurfing v Tabur Marine the Court identified the inventive concept of the patent and then asked whether the step between the prior art (or common general knowledge) was obvious to the skilled team. Importantly the Court found that the inventive concept was not just the idea of a combination product comprising both types of drug, but a combination product in which the long-acting effect of the antimicrobial drug was retained. This was considered to be implicit in claim 1 of the granted patent: “A method for producing an improved veterinary product comprising bringing a selected long-acting antimicrobial formulation into intimate admixture with…an anti-inflammatory agent…”.

The Court found that this was not a case where obviousness depends simply on whether or not it was obvious to have the bare idea of the combination (it being obvious to the skilled team that the idea, once it had been conceived, would work). In addition to establishing that the idea itself was obvious, S-P needed to show that it would have been obvious to go ahead and try the combination. In interpreting what ‘obvious to try’ means the Court followed the Court of Appeal in St Gobain where Lord Justice Jacob said 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”

Thus to succeed on obviousness S-P needed to show not only that the idea of the combination was obvious but also that it would have been obvious to go further and test the combination in circumstances where it was “more-or-less self evident” that the long-acting effect of the antimicrobial drug would be retained in the combination product i.e. there needed to be an expectation of success.

The Court was satisfied that the data in the patent shows that the long-acting antimicrobial effect of Norbrook’s long-acting oxytetracycline product is retained when it is formulated together with flunixin in a single product and that this was an unexpected benefit. On the basis of expert evidence that interaction between the drugs could adversely affect their absorption and the action of both drugs the Court found that the skilled person would not have been able to predict this result. The Court concluded that the idea of combining a long-acting antimicrobial with an anti-inflammatory (i.e. trying to ‘update’ S-P’s earlier combination product by substituting the short-acting oxytetracycline with a long-acting formulation of the same drug) would have been obvious to the skilled team, but that it would have been “far from self evident” that such a product would work in the sense that the long-acting effect of the antimicrobial would be retained. Furthermore the skilled team would not have been able to predict whether or not the inclusion of an anti-inflammatory drug would compound the irritant effects of the long-acting antimicrobial. Notwithstanding that it would have been appreciated that the product would have utility if it did work it would not have been self-evident that the combination would work and so the combination product was not ‘obvious to try’. For these reasons S-P’s obviousness attack failed.


S-P accepted the sufficiency of the specific combination of oxytetracycline and flunixin that is disclosed in the examples of the patent but challenged the broader claims that extended beyond that combination. Following the House of Lords decision in Biogen v Medeva, in which it was stated that “the specification must enable the invention to be performed to the full extent of the monopoly claimed”, the Court considered what ‘performing’ the invention actually means. Applying an even-handed approach to obviousness the Court found that for the patent to be sufficient the skilled person must be capable of making a combination of the two ingredients in which the long-acting antimicrobial effect is retained. The Court thought that it is inconceivable that all the combinations falling within the broad claims of the patent, covering essentially a combination of any long-acting antimicrobial and a non-steroidal anti-inflammatory drug, could be made to work (i.e. to retain the long-acting effect) without undue research or experiment. Norbrook argued that their patent disclosed a principle capable of general application and that following Biogen v Medeva the claims of the patent may be “in correspondingly general terms”. The Court did not accept that the patent disclosed a ‘class effect’ and applied the same reasoning as was used in Norbrook’s favour to establish an inventive step to support a finding of insufficiency. The Court said that:

“it is precisely because absorption in combination products is unpredictable that the claims need to be confined to those combinations which will work without undue research. The claims under consideration ware far too wide for that purpose”.

The fact that it was not self evident that the combination would retain its long-acting effect was fatal for sufficiency of the broader claims.


The outcome of the case is that the claims covering long-acting oxytetracycline and flunixin (Norbrook’s commercial product) were held to be valid, but the more general claims covering other combinations of antimicrobials and anti-inflammatories were found invalid for insufficiency. The decision depended upon: firstly, an appreciation that the inventive concept was more than just the idea of bringing together the two active ingredients into a combination product; and secondly, application of the test for ‘obvious to try’ set out by Lord Justice Jacob in St Gobain. The conclusions of non-obviousness (of all claims) and insufficiency of the broader claims followed inexorably from that.

The findings of the Court in the present case appear to be in sharp contrast to the pre-St Gobain case of Cipla and Others v Glaxo, a ‘combination patent’ case with many parallels to the present one (in terms of the facts). In that case the patent was found to be obvious, Pumfrey J stating that:

“the combination was an obvious combination, as a combination. It was not obvious that it would be safe, or that it would represent any advance on what had gone before. Whether this would be the case depended upon the outcome of clinical trials which was not foreseeable…”.

As this extract demonstrates, prior to St Gobain there had been a marked shift away from the old test of whether something was obvious to try with a reasonable prospect of success. Just being ‘obvious to try’ had become enough. The fact that an ‘expectation of success’ was no longer being taken into account led to accusations that the UK’s approach to the law on obviousness was out-of-step with that applied in other jurisdictions (including the EPO, Canada, the US and Australia). For example in Canada in a series of recent cases including AB Hässle v Genpharm and Sanofi-Synthelabo v Apotex the English ‘worth a try’ test was rejected in favour of a test where “the person skilled in the art must be able to say that he or she would know that the invention would work and would have the benefits associated with the invention in light of the publicly available information” (Sanofi Synthelabo v Apotex). Similarly a comparative review of the Australian and UK authorities by the Australian High Court in AB Hässle v Alphapharm reached the conclusion that the Australian law of obviousness includes the requirement of an expectation of a useful result and therefore was at odds with the (pre-St Gobain) UK law.

Patent holders should be encouraged by the judgment in S-P v Norbrook and by the fact that an apparently simple patent covering a combination product was upheld on obviousness. It suggests that the pendulum has swung back in the patentee’s favour and that an expectation of success may once again be a component of the test for obviousness. It will be interesting to see how the other Patents Court judges interpret St Gobain and whether the interpretation of Christopher Floyd QC (sitting as a Deputy High Court Judge) in this case will be endorsed by the Court of Appeal. This decision is not being appealed so we will need to wait a while longer to find out whether or not Lord Justice Jacob intended the test of ‘more-or-less self-evident’ to be of general application.

In the meantime Patentees should take heart from what now appears to be an encouraging trend.

by Scott Parker, solicitor Simmons & Simmons London

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