UK: Court of Appeal explains the limited application of the Biogen principle to product claims and upholds broad product claim protection for a novel enantiomer

09 May 2008

Trevor Cook

In a judgment given on 10 April 2008 in H. Lundbeck A/S v Generics (UK) Limited & Ors, the English Court of Appeal reversed in part the decision of the Patents Court and in so doing upheld broad product claim protection for escitalopram, the (+) enantiomer of the racemate citalopram, and that is responsible for the SSRI activity of citalopram.

The judgment is of especial significance because the Court of Appeal analysed the extent to which an attack of insufficiency, along the lines that had succeeded some ten years previously in the House of Lords in Biogen v Medeva, and that had succeeded at first instance in the Patents Court in this present case, had application to a product claim where only two synthetic routes to manufacture a product had been disclosed but the desirability of making such product was obvious. This analysis has particular authority as the leading judgment was delivered by Lord Hoffmann, who normally sits in the House of Lords, and who, when so sitting, had given the lead judgment in Biogen, but as to which he here concluded:

“40. Biogen should therefore not be read as casting any doubt upon the proposition that an inventor who finds a way to make a new product is entitled to make a product claim, even if its properties could have been fully specified in advance and the desirability of making it was obvious.”

There were three grounds of attack on the validity of the three claims of the escitalopram patent in issue:


(a) Product claims 1 and 3 lack novelty by reason of the disclosure of the racemate in the earlier published patent for citalopram;

(b) Product claims 1 and 3 and process claim 6 are invalid for obviousness;

(c) Product claims 1 and 3 are invalid for insufficiency because they claim the enantiomer made by any method, but the specification discloses only two ways of making it.


As to novelty, it was common ground, consistent with EPO and English case law (in contrast for example to that in Germany as to this issue), that the prior disclosure of a racemate did not in itself amount to a disclosure of each of its enantiomers. However it was argued that claim 1, to the enantiomer, was not only for the pure enantiomer but was also for the enantiomer as an unresolved (ie unseparated) moiety of the racemate. The Court of Appeal rejected this argument and agreed with the first instance judge, in holding that a claim to the enantiomer should be construed as not covering an unresolved part of the racemate.

As to obviousness, it was argued that the claim 6 process, one of the two claimed processes for producing the enantiomer, was obvious, along with another process that had not been disclosed or claimed. The evidence at trial had established the difficulty at the priority date of resolving citalopram (it had taken the patentees seven years to succeed in so doing), and the unpredictability of success of the 13 different approaches that might have been considered to resolve citalopram. However it was argued that claimed process had been “obvious to try”. The Court of Appeal accepted that the trial judge had correctly stated the principle to be applied as:

“The question of obviousness must be considered on the facts of each case. The court must consider the weight to be attached to any particular factor in the light of all the relevant circumstances. These may include such matters as the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort involved in pursuing them and the expectation of success.”

The Court of Appeal then accepted that the trial judge had correctly applied this principle to the facts of the case, having first noted that there were “a number of avenues of research” open to the skilled man seeking a solution to the problem and that therefore the skilled man would not have taken the claimed route unless satisfied that there was a “real prospect” that it would work, which on the evidence the trial judge found not to be established. Accordingly the Court of Appeal upheld the Patents Court judgment that neither the claimed process in issue, nor the product claims, was obvious.

As to insufficiency, the trial judge had found the escitalopram product claims to be insufficient because these were to one enantiomer of citalopram however made, when all that the patentees had discovered was one way of making that enantiomer, it being already known at the priority date that such enantiomer must exist and that either it or the other enantiomer or both must have a medicinal effect. The Court of Appeal reversed this finding. Lord Hoffmann confirmed that a product claim would usually be enabled if the specification and the common general knowledge enabled the skilled man to make it, and that for this purpose one synthetic method was enough. He explained that the Biogen case on which the trial judge had based his finding concerned not a claim as here simply to a novel product but to a type of “product by process” claim to “a molecule identified partly by the way it has been made ... and partly by what it does...” Such claim was to a class of products which satisfied the relevant conditions, one of which was that the molecule had been produced by recombinant DNA technology. Lord Hoffmann went on to observe:


“34. ... But the specification in Biogen described only one method of making the molecule by recombinant technology and disclosed no general principle. It was easy to contemplate other methods about which the specification said nothing and which would owe nothing to the matter disclosed

”35. In my opinion, therefore, the decision in Biogen is limited to the form of claim which the House of Lords was there considering and cannot be extended to an ordinary product claim in which the product is not defined by a class of processes of manufacture. It is true that the House in Biogen indorsed the general principle stated by the Board of Appeal in T409/91 Fuel Oils/EXXON [1994] OJ EPO, that—

“the extent of the patent monopoly, as defined by the claims, should correspond to the technical contribution to the art in order for it to be supported or justified.”

“36. The judge said that in holding claim 1 insufficient, he was applying this principle. But then he treated the relevant “technical contribution to the art” as being the inventive step, namely a way of making the enantiomer. That, I respectfully consider, was a mistake. When a product claim satisfies the requirements of section 1 of the 1977 Act, the technical contribution to the art is the product and not the process by which it was made, even if that process was the only inventive step.”


Lord Hoffmann then went on to explain how this approach was consistent with EPO case law, and also with the public policy justification for product claims as demonstrated by the approach to these throughout history by the courts and the legislature.

Lord Justice Jacob agreed with Lord Hoffmann's conclusions but added several valuable observations of his own. In particular he pointed out that careful thinking was called for in considering claims to desirable ends, giving the following example of one type of product claim that could still be attacked as being insufficient:

“61. So, for example, if a man finds a particular way of making a new substance which is 10 times harder than diamond, he cannot just claim “a substance which is 10 times harder than diamond.” He can claim his particular method and he can claim the actual new substance produced by his method, either by specifying its composition and structure or, if that cannot be done, by reference to the method ... but no more. The reason he cannot claim more is that he has not enabled more – he has claimed the entire class of products which have the known desirable properties yet he has only enabled one member of that class. Such a case is to be contrasted with the present where the desirable end is indeed fully enabled – that which makes it desirable forms no part of the claim limitation.”

Thus the Biogen principle still has application to product claims in certain circumstances, but not, it would seem, to product claims drawn in terms of conventionally chemical terminology, such as that in issue in the present case.