Conor Medsystems Inc. v Angiotech Pharmaceuticals, 9 July 2008 [2008] UKHL 49

The House of Lords gave important clarification of the obviousness test, and whether a patented invention is obvious where the disclosure in the patent is merely speculative. The High Court and Court of Appeal had reached views which had differed from those of the District Court of The Hague. The House of Lords decision brings the UK into line with the Dutch decision.  

Angiotech was granted a European patent for a stent coated with taxol, for use in the treatment of coronary heart disease. A stent is a tubular metal scaffold inserted into the arteries to keep them open. One problem with stents is that their insertion can cause an exaggerated healing response called restenosis, which can constrict the artery. The taxol coating inhibits this response.  

Taxol was a drug much publicised before the priority date as a possible treatment for cancer as it was anti-proliferative. Many people also thought that such anti-proliferative drugs could be used to stop restenosis. In February 1993, Angiotech discovered that taxol, amongst other drugs, inhibited the process by which capillary blood vessels grow (angiogenesis). It speculated that this may therefore prevent restenosis, as most cell tissue cannot grow much without blood. The patent therefore claimed a taxol coated stent for treating or preventing restenosis. However, while it explained how Angiotech believed it would work, it did not provide any evidence that it actually did work.  

Conor challenged the validity of the patent in the High Court, claiming that it was invalid on grounds of obviousness.  

At first instance, Pumfrey J held that the patent was obvious. He identified the contribution of the patent as being mere speculation that taxol might work to prevent restenosis (as opposed to the fact that it did work), and decided that such a suggestion was obvious. His decision was upheld by the Court of Appeal.  

Lord Hoffmann gave the leading opinion of the House, overturning the judgment of Pumfrey J and the Court of Appeal. The error which had underpinned both previous judgments was that they had incorrectly identified the invention of the patent as being mere speculation regarding the use of taxol to treat restenosis, as that was all that was disclosed in the description. Rather, the invention was a stent coated with taxol for treating and preventing restenosis, as that was what was claimed. Prima facie, the invention of a patent means that specified in the claim and it is that which must be compared with the prior art for the purpose of obviousness. The correct question in assessing obviousness was therefore whether it was obvious to use a taxol coated stent for treating or preventing restenosis. It did not matter that the patent had not demonstrated that it actually worked. The patentee is entitled to have the question of obviousness determined by reference to his claim and not some vague paraphrase based upon his extent of disclosure in the description.  

Lord Hoffmann added that, if a speculative claim is made, then the patentee is at risk of a finding of insufficiency. It will be insufficient if the invention turns out not to work. However, if it turns out that the invention does work, then it does not matter why.  

One side issue is that the House of Lords did decide that there was still a threshold test of “plausibility”, following the EPO case, John Hopkins University School of Medicine. Thus if the speculation is implausible, the patent will be invalid. Query whether that is an appropriate test. That aspect was followed in Eli Lilly & Co. v. Human Genome Sciences Inc (see below).  

The case, in fact, settled after the Court of Appeal decision and the House of Lords felt sufficiently strongly about this appeal to request the Comptroller-General of Patents to present the arguments against validity in place of Conor. Doubtless that was because of the differing judgment of the Dutch court. As Lord Hoffmann states, “when the question is one of principle, it is desirable so far as possible there should be uniformity in the way the national courts and the EPO interpret the European Patent Convention.” This marks a general trend this year towards following other European national courts and the EPO, when appropriate.