House of Lords clarifies how one identifies the ‘inventive step’ of a patent

A recent decision of the House of Lords clarified how one identifies the inventive step of a patent. In particular, the House of Lords clarified that, although a patent may not be merely speculative, it was not necessary that the patent taught that the invention worked. If a specification discloses enough to make the invention plausible, there is no reason why the test of obviousness should differ to the test employed when the efficacy of the invention is justified by experiment. In addressing the question of whether the specification disclosed sufficient information to determine whether the invention was “obvious to try without an expectation of success” the Court of Appeal had made “an illegitimate amalgam of the requirements of inventiveness and either sufficiency or support or both”. As such, the Court of Appeal was wrong not to apply the ordinary principles of obviousness to the claimed invention. Their Lordships also indicated that the ‘obvious to try’ test is not always appropriate to high value technological developments. The validity of the patent was therefore restored.

The decision is very significant and is a further demonstration of a more pro-patentee approach being demonstrated recently by the English courts, particularly in pharmaceutical cases. The decision will make challenges to the validity of a patent on the grounds of obviousness harder to sustain, especially those relying upon a line of argument that a course of action was “obvious to try”.

Background

Angiotech Pharmaceuticals Inc. (“Angiotech”) owned a patent for a stent coated with polymer loaded with the anti-proliferative drug paclitaxol. However, the patent claims did not refer to paclitaxol exclusively but stated that a wide variety of other “anti-angiogenic” agents might be utilised within the context of the disclosure.

A stent is a tubular metal scaffold used to keep an artery open after angioplasty, a method of surgery for dilating an artery affected by atherosclerosis. However, a serious and common side effect of the insertion of a stent is restenosis. This is when the insertion of the stent causes the proliferation of new tissue cells, which then restrict the artery. The side effect can be prevented by use of the patented stent, which is loaded with the anti-proliferative drug, paclitaxol, known commercially as taxol.

Angiotech licensed the patent exclusively to Boston Scientific, a manufacturer of stents. Conor Medsystems Inc. (“Conor”) is a competitor of Boston Scientific and it sought revocation of the patent on the basis that it was obvious. Conor said that the inventive concept of the patent “lies in the idea of trying some, one or more, taxol/polymer combinations to determine whether restenosis can thereby be treated”. Conor said that it was obvious that taxol was “worth a try” and as the patent did not disclose that the idea works to any particular extent, it was not required to show that it was obvious to use taxol to treat restenosis.

In the High Court, Pumfrey J held that the patent must be revoked on the basis of invalidity in view of cited prior art. Pumfrey J found that the patent’s disclosure was that “taxol should be incorporated in a drug-eluting coating on a stent with a view to seeing whether it was safe and was of any use in the treatment or prevention of restenosis”. The inventive step was therefore the idea that it was worth testing anti-proliferative drugs as a coating to the stent without any expectation of success. Pumfrey J held that this idea was obvious to the skilled person. He said that the specification gave no indication of any likelihood of success and no indication as to side effects, toxicity or efficacy. Therefore, these factors were not relevant considerations when assessing the obviousness of testing taxol.

The Court of Appeal then upheld the decision. The Court found that the patentees had not made an invention by specifically proposing taxol as opposed to any other anti-angiogenics because the specification did not indicate that taxol actually worked to prevent restenosis. The skilled person on reading the prior art would have naturally thought of taxol as a candidate and, therefore, the patent was invalid for obviousness. According to Jacob LJ, “just adding another, self-evident candidate to a list of things which might be investigated was not enough to make an invention”.

The House of Lords

Following the decision of the Court of Appeal, Angiotech and Conor reached a settlement. However, the House of Lords said that a patent confers proprietary rights in rem and the validity of a patent cannot be established simply by a judgment in default of opposition. It therefore invited the Patent Office to present arguments against the validity of the patent. It was commented upon that the case concerned a question of principle, the identification of the “inventive step”, and that the Dutch court had upheld the validity of the equivalent patent.

On 9 July 2008, the House of Lords allowed the appeal and affirmed the validity of Angiotech’s patent.

Lord Hoffmann firmly rejected Conor’s definition of the inventive concept, saying “I shall say at once that in my opinion this argument was an illegitimate amalgam of the requirements of inventiveness and either sufficiency or support or both.” Hoffmann J went on to state that it is the invention which has to involve an inventive step. The invention was a stent coated with taxol, a new product. The inventive step was that the product would have a particular property, in that it would prevent or treat restenosis. The question of obviousness was therefore “whether it was obvious to use a taxol-coated stent for this purpose”.

In respect of ‘obvious to try’ arguments, Lord Hoffmann said that “it is hard to see how the notion that something is worth trying or might have some effect can be described as an invention in respect of which anyone would be entitled to a monopoly”. He was therefore not surprised that Pumfrey J had to subject this type of invention to a test of whether it was obvious to try it without expectation of success, even though this was an oxymoronic concept.

According to Lord Hoffmann, although a patent may not be merely speculative, it was not necessary that the patent taught that the invention worked; it was only necessary to teach that taxol was the best anti-angiogenic to use. He agreed with the Dutch court that the patent did this by indicating that taxol scored well in the CAM assay. Lord Hoffmann commented that if a specification discloses enough to make the invention plausible, there is no reason why the test of obviousness should differ to the test employed when the efficacy of the invention is justified by experiment. As such, the Court of Appeal was wrong not to apply the ordinary principles of obviousness to the claimed invention. The patent was therefore upheld.

Comment

The case makes invalidity attacks on the basis of ‘obvious to try’ less likely. In finding that the High Court and Court of Appeal had wrongly identified the inventive step by focusing too closely on the specification rather than the claim itself, the House of Lords applied a straightforward test of obviousness and found the patent valid. It was not necessary, in assessing obviousness, to consider whether there was a reasonable expectation of success to experiments that may have been obvious to try. The decision will be welcomed by patent owners.

Angiotech nearly invalidated their patent by losing the actual invention in the midst of the wide specification as initially drafted. This highlights the importance of accurate drafting, enabling clear determination of the invention.