House of Lords upholds validity Angiotech stent patent

09 July 2008

Trevor Cook, Neil Jenkins

In its judgment given today in Conor Medsystems v Angiotech Pharmaceuticals, the House of Lords has reversed judgments of the Patents Court in 2006 and the Court of Appeal early in 2007 that had both found the UK designation of EP 0 706 376 B, Angiotech’s patent for a stent coated with the drug taxol, to be obvious and thus invalid for lacking inventive step. In so doing it agreed with, and quoted various passages from, a decision of the District Court of The Hague that had rejected the attack of lack of inventive step in respect of the Dutch designation of the patent. In contrast to some of its other decisions in the patent field, the judgment of the House of Lords in this case is an exercise in judicial restraint and will be a disappointment for those who were looking for new statements of principle as to the law of obviousness, perhaps in recognition of the dangers of so doing given the irreducible subjectivity of obviousness determinations. Instead it focuses on the specific issue in this case with which the House of Lords disagreed with the lower English courts. But in so doing, it also makes an important contribution to the debate as to the relevance of attacks on inventive step based on an “obvious to try” approach.

Conor were no longer a party to the action, the parties having settled as between them their disputes under these patents in the summer of 2007. However, in order that Angiotech could secure the opportunity in the House of Lords to try to reverse the decision of the Court of Appeal and restore their patent, they had to pay for the UK Patent Office to instruct counsel to argue Conor’s case in its place. The Angiotech patent was directed to providing a solution to the problem of restenosis, a condition encountered with ordinary stents (tubular metal scaffolds inserted into an artery to keep it open) where the injury caused to the inner layer of an artery by their insertion could produce an exaggerated healing response that restored the original constriction in the artery that the stent was meant to treat.

The lead judgment of the House of Lords was given, as has become usual in their judgments in patent cases, by Lord Hoffmann, who recognised that although it was inevitable in the present system of litigation in Europe that national courts would occasionally make inconsistent decisions on differing national designations of a European patent (especially where dealing with questions of degree as arose with obviousness), it was undesirable that there be differences as between them in principle, as had been the case here. He identified the principle in this case as being how one identified the concept embodied in the invention for the purposes of determining inventive step. In essence, the lower English courts had erred by so formulating the inventive concept as to incorporate insufficiency type concerns (based on the failure of the specification to set out data showing that the invention did actually provide the promised benefit, that of preventing restenosis), in their analysis of inventive step:

“19 … the invention is the product specified in a claim and the patentee is entitled to have the question of obviousness determined by reference to his claim and not to some vague paraphrase based upon the extent of his disclosure in the description. There is no requirement in the EPC or the statute that the specification must demonstrate by experiment that the invention will work or explain why it will work. …”

There were cases, such as T 1329/04 in the EPO, where patents were found to lack inventive step because they disclosed nothing more than speculation that did not go beyond what was obvious. But these were far from the facts of this case, where there was some teaching in the specification, based on a particular assay, indicating that it was advantageous to use taxol to prevent or treat restenosis, and so passed the threshold test of making the invention plausible:

“37 … there is … no reason as a matter of principle why, if a specification passes the threshold test of disclosing enough to make the invention plausible, the question of obviousness should be subject to a different test according to the amount of evidence which the patentee presents to justify a conclusion that his patent will work. …”

Here the claim in issue was to a stent coated with taxol, the novelty of which was unchallenged. The alleged inventiveness lay not in discovering how to make it but in the claim that such a product would have a particular property, namely, the prevention or treatment of restenosis. Thus the relevant question was whether it was obvious to use a taxol coated stent for this purpose, but the lower English courts had failed to address this.

The correct test that they should have applied, according to Lord Hoffmann, was whether it could be shown on the basis of the prior art that “that the skilled person would have an expectation of success sufficient to induce him to incorporate taxol in a drug eluting stent?” Lord Hoffmann inferred from other observations in the English judgment at first instance that the trial judge would have answered this question in the negative and so rejected the attack, a view which accorded with his own on the basis of the prior art references themselves and the expert evidence that had been before the judge.

Another member of the House of Lords, Lord Walker, although agreeing, as with other members of the House, with Lord Hoffmann, added some observations on the relevance of the “obvious to try” approach, as to which Lord Hoffmann had observed that the notion was useful only in cases in which there was fair expectation of success, and that how much of an expectation would be needed depended upon the particular facts of the case. Lord Walker pointed out that the expression’s origins lay in a forty year old case (Johns-Manville Corporation’s Patent) that was concerned with “a fairly low tech process” and observed that with the increase since then in the volume of high technology research, especially in the fields of pharmaceuticals and biotechnology, the expression had taken on a life of its own. However he then quoted some observations by the retired Patents Court Judge, Sir Hugh Laddie, as to the problems with this approach, and by Lord Justice Jacob, in the Court of Appeal in this case, as to its limited application. Although Lord Walker did not endorse these in terms, it would seem that these opinions are viewed sympathetically by the House of Lords, and that it will be rare that an inventive step attack based on an “obvious to try” approach will succeed in the English courts in future.

The wider consequences of this decision of the House of Lords may however be limited because there has already (with the exception of this particular case, where insufficiency considerations impermissibly crept into an inventive step analysis), been a discernable shift in approach on the part of the English Patents Court and the Court of Appeal, especially in the pharmaceuticals and medical device areas, which have become increasingly reluctant to hold patents invalid for lack of inventive step.