In its judgment of 25 February, the House of Lords rejected an appeal by Generics (UK) and three other generic pharmaceutical companies from the Court of Appeal’s finding that Lundbeck’s European Patent (UK) 0,347,060 was not invalid on the grounds of insufficient disclosure of the invention (see Newsletter of May 2008). The case concerned a patent with claims directed to the synthesis of the (+) enantiomer of citalopram where the existence of the enantiomer was known as part of a racemic mixture of the (+) and (-) enantiomers, but a method of separation or stereoselective synthesis of the (+) enantiomer was not. The allegation of insufficiency arose from the fact that whereas the specification only disclosed one route of stereoselective synthesis (the so-called diol route and two alternative methods of implementing it) the claims covered all methods of obtaining the (+) enantiomer. The judge at first instance applied the House of Lords decision in Biogen [1997 RPC 1] in finding the patent invalid for insufficiency but the Court of Appeal reversed the judgment, explaining the limited application of the ratio in Biogen. The House of Lords has now explained the error of the Patents Court even more clearly by pointing out that there is a fundamental distinction between a claim covering multiple embodiments where they are not enabled by the specification across the scope of the claim and on the other hand a claim to a single embodiment where all methods of obtaining it are not necessarily enabled. Their Lordships (Phillips, Scott, Walker, Mance and Neuberger) considered the law on insufficiency and the distinction between process, product-byprocess and product claims at some length but as Lord Walker stated the following passage from the EPO Technical Board of Appeal in Exxon (T 409/91) makes the distinction most clearly:

“In the Board’s judgment, this case differs from those where a class of chemical compounds is claimed and only one method of preparing them is necessary to enable a skilled person to carry out the invention, in other words, to prepare all compounds of the claimed class. Rather, the present case is comparable to cases where a group of chemical compounds is claimed, and not all of the claimed compounds can be prepared by the methods disclosed in the description or being part of the common general knowledge (see, for example, T 206/83, OJ EPO 1987, 5). In the latter case, it was not held sufficient for the purpose of Article 83 EPC to disclose a method of obtaining only some members of the claimed class of chemical compositions.”

As Lord Walker pointed out, in this case Lundbeck’s claim 1 was to a single chemical composition and therefore fell outside the vice addressed by Exxon – whereas of course Biogen represented an application of the above-quoted principle.