This article was first published in Issue 56 of IPPro Life Sciences.

In May 2014, Justice Richard Arnold delivered his judgement following trial in Actavis v Eli Lilly (2015, RPC 6) in the UK, holding that the file wrapper for a patent could be taken into account in construing its claims, particularly where a patentee had narrowed the claims to achieve grant but subsequently argued a broader construction to catch an infringer. In its June 2015 judgement (2015, EWCA Civ 555), however, the Court of Appeal disagreed, stating that it would be “a very rare case indeed” in which the prosecution history would be helpful to the court.

The Court of Appeal’s ruling is also of significant interest for its decision on the ability of the English court to give declarations of noninfringement under foreign designations of a European patent. Actavis had sought such declarations under the French, Italian and Spanish designations as well as the UK designation. Justice Arnold rejected Eli Lilly’s counter-argument that each jurisdiction’s rules on admissibility should apply to Actavis’s claim, not just the English rules. The Court of Appeal agreed with him.

File wrappers and construction

The action concerned Eli Lilly’s European patent protecting the formulation of its cancer treatment Alimta. The patent as granted claims the active ingredient, pemetrexed disodium (an antifolate), in combination with vitamin B12 and, optionally, a folic protein binding agent. At the start of the prosecution process, the claims had been considerably wider, referring to an antifolate generally before being narrowed to “pemetrexed” as a free-standing descriptor in response to an objection by the examiner. But the examiner objected to that amendment as well, saying that it added subject matter as pemetrexed was a distinct compound to pemetrexed disodium, the one referred to in the patent’s specification. Eli Lilly therefore further limited the claims to pemetrexed disodium, reserving the right to file divisionals for other patentable subject matter but never in fact doing so.

Actavis developed generic versions of Alimta containing one of pemetrexed diacid, pemetrexed dipotasium or pemetrexed dimethamine, and sought declarations from the English court that, as they did not contain the disodium salt, they did not infringe the designations of Eli Lily’s patent.

At the time of Justice Arnold’s judgement, little use of file wrappers had been made in English patent actions since the October 2004 judgement of Lord Leonard Hoffmann in Kirin- Amgen v Hoescht Marion Roussel (2005, RPC 9). Lord Hoffman had said that there were good reasons why the English courts discouraged, if not actually prohibited, the use of patent office files in aid of the construction of claims. The reasons included that the meaning of a patent does not change depending on whether a party has access to the office file or not, and anyway the file may reflect no more than a patentee’s desire to get the patent granted quickly without further argument with the examiner. In short, it was a difficult and likely unproductive exercise to use the file wrapper to try to work out what the patentee meant by a claim’s terms.

Justice Christopher Floyd (as he then was) had taken matters further by warning in Qualcomm v Nokia (2008, EWHC 329 (Pat)) that it was positively counterproductive to be referred to prosecution documents as it alerted the tribunal to the fact that there might be something to be said for the alternative construction.

Despite such dicta, Actavis persuaded Justice Arnold that there were limited circumstances in which it was appropriate to take note of the prosecution history when construing a patent’s claim. One such circumstance was that of the patentee that, having limited its claims to allow grant, subsequently regretted that decision when later forced to argue a wider construction on infringement. Eli Lilly was such a “regretful” patentee having narrowed its patent to permetrexed disodium, thereby potentially enabling Actavis to circumvent it.

The Court of Appeal’s judgement was given by Lord Justice Floyd (as he now is), who maintained his earlier disapproval of the use of file wrappers. First, their use assumed that the skilled reader always read the prosecution history, which he considered doubtful given their limited value. Second, it assumed the prosecution history would assist the court. But, as there is no file wrapper estoppel, it did not as there was always the question of whether the patentee actually needed to accept the limitations to its claims. Therefore, if an alleged infringer wanted to argue that the patentee’s construction lacked support from the specification, it should argue that directly rather than going via the prosecution history.

Declarations of non-infringement

As mentioned, Actavis sought declarations that its generic versions of Alimta did not infringe the UK, French, Italian and Spanish designations of Eli Lilly’s patent. At the outset, the German designation was included, but it was dropped after Eli Lilly brought infringement proceedings in Dusseldorf, which that court accepted, rejecting Actavis’s jurisdictional challenge based on the English court being first seized. In the UK, Actavis argued at first instance and on appeal that it was entitled to declarations in respect of each designation as it had complied with the English rules on admissibility of its claim. These were the relevant rules as entitlement to a declaration was a procedural rather than a substantive matter (so English law applied as the lex fori).

Eli Lilly countered that the declaration requests regarding the non-UK designations were inadmissible because, under the Rome II Regulation (864/2007/EC), the local rules on standing for each designation for which a declaration was sought had to be applied.

Justice Arnold agreed with Actavis on the issue but found that, even if each designation’s national rules did apply, Actavis had complied with them. He further found that Actavis’s generic versions of Alimta did not directly or indirectly infringe the patent because at no stage was Actavis making a medicament that contained pemetrexed disodium.

While the Court of Appeal agreed with Justice Arnold that English law determined admissibility, it disagreed on infringement. There was no direct infringement because none of Actavis’s formulations (a concentrated solution and a lyophilised powder) contained sodium ions, but, when the formulations were mixed with saline by medical staff prior to administration to the patient by a drip, sufficient sodium ions were present to say that pemetrexed disodium was present. Accordingly, there was indirect infringement. The action is now remitted to the first instance court to determine whether or not mixing with a dextrose solution instead of saline would infringe.

To Lord Justice Floyd’s regret, the Court of Appeal was not asked to decide whether the prosecution history is altogether inadmissible in English patent proceedings. As he observed, a rule that only discourages it use has disadvantages such as the costs that will inevitably be incurred by parties deploying the material on the off chance it is considered helpful. But, reluctantly, he had to leave it there. However, his comments should further discourage parties from referring to file wrappers at trial and put them at risk on costs if they do.

As regards the English court’s ability to grant declarations under non-UK designations of European patents, the Court of Appeal’s decision resolves favourably a long-standing debate. Pending the coming into operation of the EU’s Unified Patent Court, and for patents that are opted-out of that system, it makes the English patents courts a potentially useful forum for resolving pan-European patent disputes where validity is not an issue.

This is not just for generic pharmaceutical companies such as Actavis seeking to clear the path to market, but for any company that considers it has achieved a design-around and wants the reassurance and commercial certainty of a court decision confirming non-infringement of a European patent without having to go to each national court separately.