Merrell Dow Pharmaceuticals Inc v HN Norton & Co Ltd

The House of Lords held that claim 24 to the acid metabolite was not novel because it formed part of the state of the art by virtue of disclosure in the earlier terfenadine patent specification. The court construed the Patents Act 1977 (in particular section 2 and section 1(1)(a)) in the light of Article 54 EPC and concluded that prior public disclosure which enables the public to perform the claimed invention destroys novelty. Secret or uninformative prior use does not make matter part of the state of the art under section 2(2); only uses or disclosures that make the necessary information available to the public will do so. Applying these principles, the terfenadine specification taught the making of the metabolite in the body by ingestion of terfenadine and thus anticipated the later claim to the metabolite when made in the human body.

This appeal concerned a patent claim to an acid metabolite formed in the human body after ingestion of terfenadine. Merrell Dow, proprietor of an earlier terfenadine patent (now expired), obtained a later patent claiming the acid metabolite and sued competitors for infringement. The defendants applied to strike out the actions on grounds including lack of novelty. The point heard by the House of Lords was whether the making of the acid metabolite in the human body (by ingestion of terfenadine) was part of the state of the art before the priority date of the later patent.

The issues framed were whether prior use by volunteers (clinical trials) or the disclosure in the terfenadine patent specification anticipated the acid metabolite claim under section 2(2) and section 1(1)(a) of the Patents Act 1977, interpreted alongside Article 54 EPC; and whether secret or uninformative prior use could defeat novelty under the 1977 Act.

The court analysed the difference between the old law (under the Patents Act 1949) and the 1977 Act/EPC regime. It held that under section 2(2) matter is part of the state of the art only if information about the invention has been made available to the public. Secret or uninformative prior use (acts that convey no enabling information) do not, by themselves, make the invention part of the state of the art. Conversely, where a prior disclosure (for example a patent specification) communicates sufficient information that the public can work the claimed invention in the asserted form, novelty is destroyed. Applying these principles the House held that the terfenadine specification disclosed the necessary information — in the form of instructions to make and use terfenadine and its effect in producing the metabolite in the body — and that this disclosure made the acid metabolite, insofar as made in the human body by ingestion of terfenadine, part of the state of the art. The appeal was dismissed.

Appeal dismissed. The House held that under the Patents Act 1977 (construed in conformity with Article 54 EPC) novelty requires that the invention was not previously made available to the public by disclosure or use that conveys the necessary enabling information. Secret or uninformative prior use does not defeat novelty, but the terfenadine patent specification did disclose sufficient information to make the acid metabolite (as produced in the human body by ingestion of terfenadine) part of the state of the art and therefore not new.

The actions were struck out at first instance by Aldous J. on the ground that the patent was invalid for lack of novelty. That decision was affirmed by the Court of Appeal (order of 16 February 1994). The House of Lords dismissed the appeal and affirmed the Court of Appeal's order [1995] UKHL 14.