In Conor Medsystems Inc v Angiotech Pharmaceuticals Inc, the House of Lords has delivered a key decision clarifying the law in relation to whether a patented invention is “obvious”. In coming to this decision the House of Lords overturned the decisions of both the High Court and the Court of Appeal and criticised the approach to the assessment of inventive step adopted in the earlier proceedings. The House of Lords stated that the issue of inventive step should be determined by reference to the claims, whose purpose is to define the invention, and not by considering the extent of the supporting evidence supplied in the description.

The Patent

The patent concerned a stent coated in Taxol®. Stents are commonly used following surgery to enlarge narrowed coronary arteries, the stent serving to prevent restenosis (re-narrowing) of the arteries. A common problem with stents, however, is that their very insertion can lead to the local proliferation of blood vessel cells (angiogenesis), resulting in restenosis. The release of Taxol® from the Angiotech stent is intended to inhibit restenosis by preventing the angiogenesis. It was claimed by Conor that it was obvious to try using Taxol® to inhibit restenosis, and hence the claimed stent lacked an inventive step.

High Court and Court of Appeal Decisions

Both the High Court and the Court of Appeal found in favour of Conor, revoking the patent for lack of inventive step.

One aspect of the finding of obviousness in the High Court and Court of Appeal was the lack of experimental evidence provided in the specification that a Taxol®-coated stent actually reduced restenosis. For this reason it was felt that the invention was merely a proposal that Taxol® might be useful in this application, and that all Conor had to do was to prove that it would have been obvious to consider trying Taxol®, rather than that it would have been obvious to actually carry out the claimed invention. As the prior art teaching was such that the skilled person would not dismiss Taxol® immediately, the lower courts felt that the skilled person would experiment with Taxol® and hence the patent was invalid for lack of inventive step.

Interestingly, the Court of Appeal decision was handed down the day before the Dutch Patents Court found the Dutch equivalent patent valid, dismissing the arguments put forward by Conor and finding an inventive step to be present.

House of Lords Decision

The House of Lords criticised the approach of the lower courts stating that there was no requirement in the law on obviousness to prove that the invention works. The law requires that the patent teaches how to make the invention work, but this does not form part of the inventive step requirement. Instead, all that is required to fulfil the inventive step requirement is that the invention will plausibly work, based on the contents of the patent specification (assuming, of course, that the claimed invention, once considered plausible, is not obvious over the prior art). The Angiotech patent contained data (an angiogenesis-inhibition assay) showing it was plausible that a Taxol®-coated stent would prevent or treat restenosis. Accordingly, and since the prior art did not contain a clear pointer that Taxol® could be used in this way, the criteria for inventive step were met.

As a result, the House of Lords overturned the Court of Appeal decision.

Significance

This decision is significant in that it offers a clear guideline as to the amount of evidence required in a patent application to satisfy the inventive step requirement. In essence, it seems that the amount of evidence may be rather low, provided the ‘plausibility’ threshold is overcome. It is possible that this simplification will result in a more patentee-friendly environment in the UK, with more patents being upheld.

The decision is also interesting in that the Law Lords took the opportunity to remind us that the European Patent Office and the national courts across Europe should offer a consistent approach to the interpretation of the European Patent Convention wherever possible. In this case, they believed that the Dutch Court had correctly identified the test for inventive step, and as a result had correctly held that the patented invention was not obvious.

Dr Joanna Westwood
Dr Nicholas Jones
Life Sciences & Chemistry Group

July 2008