Precisely delineated claims and the Protocol to Article 69: two cases, two views

From our friends Brian Whitehead, Stuart Jackson and Richard Kempner of Kempner and Partners comes this handy note on some very dramatic patent litigation from England and Wales which comes under their stern scrutiny. This is what they write:

Following on from yesterday’s decision in Smith & Nephew Plc v ConvaTec Technologies Inc [noted briefly on the IPKat here], the Court of Appeal for England and Wales has today handed down another decision in relation to patents in the healthcare sector in Actavis UK Ltd v Eli Lilly & Company [2015] EWCA Civ 555.  Actavis applied for declarations of non-infringement (DNIs) in respect of the UK, French, Italian and Spanish designations of European Patent No. 1 313 508.  That patent is drafted in the Swiss form, and claim 1 is for “Use of pemetrexed disodium in the manufacture of a medicament ...”.  Actavis’ proposed product contained pemetrexed in one of three different forms: the free acid, or the ditromethamine or dipotassium salts (non-chemist readers are referred to paragraphs 76-79 of Arnold J’s decision, in which an explanation of the various terms is given).

In assessing whether there was direct infringement, unusually both Arnold J at first instance and Floyd LJ on appeal applied the Improver three-stage test – rarely applied since the seminal decision in Kirin-Amgen.  Both at first instance and on appeal, it was held that there was no direct infringement.  We can agree with that – clearly, for example, the potassium salt of an acid is a different chemical entity to the sodium salt, and it is difficult to see how “sodium” could be construed to cover “potassium”.  In any case, the sodium and potassium salts may have different properties and would require separate efficacy and safety tests.

The Court of Appeal disagreed with Arnold J, however, on the issue of indirect infringement.  The medical practitioner utilising Actavis’s proposed product is required to dissolve it in a saline solution.  That would provide an excess of sodium ions, with the result that the solution would contain, amongst other things, pemetrexed and sodium ions.  Arnold J took the view that the reference to “pemetrexed disodium” in the claim is to the solid form of that substance.  Floyd LJ disagreed, holding that

“the skilled team, particularly the chemist, would understand from the 508 patent that pemetrexed disodium is also used to refer to solutions which contain pemetrexed ions and sodium ions in solution”.   

Applying that construction, Floyd LJ held that pemetrexed dipotassium is a means relating to an essential element of the invention, and therefore the Actavis product infringes under s. 60(2) of the Patents Act 1977. 

Whereas we can follow the logic of Floyd LJ’s approach, we believe that it leads to a rather arbitrary outcome, and that Arnold J’s approach was to be preferred.  The saline solution is nothing more than an inert carrier, and if Actavis’s formulation was dissolved in another (non sodium-containing) carrier, infringement under s. 60(2) would presumably not have been made out.  In fact, according to the postscript to the judgment Actavis has now asked for a declaration of non-infringement in respect of its same formulation but using a dextrose solution instead of a saline solution.

The decision raises a number of other very interesting issues, particularly on whether (and if so under what rules) the English courts can grant declarations of non-infringement for other countries’ designations of European patents.  Doubtless these issues will be the subject of commentary, but for the time being we have focussed only on the patent construction point.

The authors, two of whom are former research chemists, also have a comment on the ConvaTec decision. We find the outcome of Kitchin LJ’s approach to be problematic, in that we cannot see how the skilled person could possibly consider a concentration of 0.5% as falling within a claimed range of "between 1 per cent and 25 per cent".  We respectfully disagree with the approaches of both Birss J and Kitchin LJ.  In our view, the skilled person would understand that reagent concentrations can never be absolutely precise, but are subject to a margin of error.  What is an acceptable margin of error will depend upon the particular purpose of the reagent.  Kitchin LJ considered that “it is clear from the teaching of the specification that the binding agent concentration is not critical in the method of this invention”.  In the circumstances, we consider that whereas the skilled person would not necessarily prepare and measure the concentration of the silver solution to the highest degree of precision (it was undisputed that the concentration can be measured to a precision of at least two decimal places), he would still prepare and measure it with a reasonable degree of accuracy.  A minimum accuracy of 10% would, we suggest, be appropriate, as that is easily achievable even without using microbalances and calibrated volumetric flasks.  That would imply that the range covered by "between 1 per cent and 25 per cent" is, at its widest, 0.9-27.5%.  The chemist (one of the members of the skilled addressee as determined by Birss J) would be unlikely even to consider the concept of significant figures, which seems to form the basis of the judge’s thinking, even if he recalled the concept from school mathematics studies.  He would, though, expect a reasonable degree of accuracy in preparation of stock solutions, even for applications not requiring a high level of precision.  A margin of error of 50%, as suggested by Kitchin LJ’s approach, would in our view be regarded as unacceptable by the chemist.  Indeed, we would challenge the competence of any lab technician who made up such a solution.

Whereas this and yesterday’s ConvaTec decision may appear to have little in common, when read together they raise an interesting issue relating to patent construction.  All readers will be familiar with the Protocol to Article 69 of the European Patent Convention (EPC), which states that claims are to be construed in such a way as to combine fair protection for the patentee with reasonable certainty for third parties.  The judges in both cases expressly referred to the Protocol, and satisfied themselves that their construction of the patents satisfied its requirements.  Given that, we consider it surprising that two patent claims, which appear on their face to be very precisely delineated, can have given rise to such a divergence of views by judges in the Courts of England and Wales.  Whereas the patentees will presumably be highly satisfied with the degree of protection they have been given, we are not sure that the results can be said to provide “reasonable certainty for third parties”.  We shall have to see whether the Supreme Court will agree to hear appeals from either, and if so whether they will disagree with one (or both!) of the courts in either case.