Patents: invalidity for insufficiency across broad range of products claimed


The Supreme Court has held that two patents for a transgenic mouse used for the development of human antibodies were invalid for insufficiency.


A patent may be revoked if its specification does not disclose the invention clearly and completely enough for it to be performed by a person skilled in the art (section 72(1)(c), Patents Act 1977).

A European patent application must disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (Article 83, European Patent Convention) (EPC) (Article 83). Patent claims must be clear and concise and supported by the description (Article 84, EPC) (Article 84). Articles 83 and 84 give effect to the legal principle that a patent monopoly must be justified by the technical contribution to the art that the disclosure of the invention has made.


R sued K for infringement of two patents relating to the production of human antibodies using transgenic mice. These patents were based on a gene manipulation technique which inserted human gene elements involved in generating antibodies into a section of the corresponding mouse gene, overcoming a known problem which arose, resulting in mice suffering from a reduced immune response, or immunological sickness, which seriously impaired their efficiency as platforms for antibody development. 

The High Court held that the patents were invalid for insufficiency, but that, if they had been valid, K infringed some of the claims. Both parties appealed. The Court of Appeal reversed the High Court's decision and held that the patents were valid and infringed. K appealed.


The court allowed the appeal and held that the patents invalid for insufficiency.

The key question is whether a product patent, the teaching of which enables the skilled person only to make some, but not all, of the types of product within the scope of the claim, passes the sufficiency test, where the invention would contribute to the utility of all the products in the range, if and when they could be made. The court held that the claims must be considered as directed to a product, and, at the priority date, the description in the patent did not enable the skilled person to make that product over the whole claimed range. In particular, what was enabled was the less valuable part of the range. Here, the product as currently made and marketed by both parties, which was undoubtedly of great value, was at the end of the range, which could only be made after further inventive developments by both parties. The Court of Appeal had wrongly concentrated on the inventive concept rather than on the claimed product which incorporated that invention.

Several key legal principles underlie the law of sufficiency. In the case of a product claim, the contribution to the art is the ability of the skilled person to make the product itself, rather than the invention, if different. The disclosure required of the patentee is that which would, together with the common general knowledge existing as at the priority date, be

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