Conor Medsystems Incorporated (Respondents) v Angiotech Pharmaceuticals Incorporated and others (Appellants)

Obviousness must be assessed by reference to the invention specified in the claim. A court must not dilute a product claim into a mere proposal for experimentation because the description contains limited supporting evidence.

Inventiveness is distinct from sufficiency and support. A specification need not contain experimental proof that the invention works or explain its mechanism, provided its disclosure makes the claimed solution plausible.

An invention is not obvious merely because it was worth trying. An “obvious to try” analysis requires a fair expectation of success, assessed in light of the motive to solve the problem, the available avenues of research, the effort involved and the expected prospect of success. A candidate drawn from many undifferentiated possibilities, without such an expectation, will not ordinarily satisfy that standard.

Conor Medsystems Incorporated v Angiotech Pharmaceuticals Incorporated concerned claim 12 of a European patent for a taxol-coated stent used to treat or prevent recurrent stenosis. Conor sought revocation for obviousness by reference to three items of prior art. Pumfrey J revoked the patent, and the Court of Appeal upheld that decision in [2007] EWCA Civ 5.

The lower courts treated the patent as disclosing no more than that taxol was worth testing on a stent. A parallel challenge before the District Court of The Hague failed because the Dutch court construed the specification as teaching that taxol should be used to prevent restenosis.

After the parties settled, Conor did not oppose Angiotech’s appeal. Because patent validity could not be established by default, the House invited the Comptroller General of Patents to present the arguments against validity. The central issue was whether obviousness should be assessed against the claimed therapeutic use or against the weaker proposition that taxol was merely worth trying.

1. Appeal allowed unanimously. Lord Hoffmann delivered the leading opinion. Lord Scott, Baroness Hale and Lord Walker agreed with his reasons, while Lord Neuberger agreed with both Lord Hoffmann and Lord Walker. The patent was upheld.

2. Per Lord Hoffmann, the claimed invention had to be identified from the claim, consistently with section 125(1) of the Patents Act 1977. Claim 12 specified a taxol-coated stent for preventing or treating restenosis. Although making the product involved no inventive technique, the claimed therapeutic property could supply the inventive step. The claim could not be reduced, by reference to perceived deficiencies in the description, to a proposal that taxol should merely be tested.

3. Per Lord Hoffmann, the lower courts had illegitimately amalgamated inventiveness with sufficiency or support. Neither the European Patent Convention nor the Patents Act 1977 required experimental proof that the invention would work or an explanation of why it would work. The specification taught that taxol should be used and supported that teaching through the CAM assay. If the claimed effect had been false, insufficiency could have arisen; but the invention did work, and its precise mechanism was immaterial.

   A merely speculative assertion must still pass the threshold of plausibility. The EPO authorities concerning unsupported classes of compounds or post-published evidence were distinguishable because the taxol claim was plausible and implausibility had neither been pleaded nor argued. Once that threshold was passed, the obviousness test did not vary according to the quantity of evidence presented in the specification.

4. Per Lord Hoffmann, an “obvious to try” analysis is useful only where there is a fair expectation of success. The necessary expectation depends on all the circumstances, including the motive to solve the problem, the available research avenues, the effort required and the expected prospect of success. Treating experimentation undertaken without any expectation of success as sufficient was erroneous.

   Lord Walker added that “obvious to try” was not a technical doctrine or universal verbal formula. Modern research incentives may make many low-probability avenues commercially worth exploring, without making each resulting solution legally obvious.

5. Neither Wolff nor Kopia identified taxol as particularly suitable for preventing restenosis. They left the skilled person facing many possible drugs. Katsuda’s in vitro evidence that taxol inhibited smooth-muscle-cell proliferation also did not make the claimed use obvious. The prior art therefore failed to establish the required inventive-step challenge under article 56 of the European Patent Convention and section 1(1)(b) of the Patents Act 1977.

1. House of Lords: In Conor Medsystems Incorporated v Angiotech Pharmaceuticals Incorporated [2008] UKHL 49, the House unanimously allowed the patentees’ appeal and upheld the patent.
2. Court of Appeal: In [2007] EWCA Civ 5, the court upheld Pumfrey J’s conclusion that the claimed invention was obvious.
3. High Court: Pumfrey J allowed Conor’s revocation challenge. He treated the specification as contributing only the proposal that a taxol-coated stent should be tested for safety and efficacy.