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How many moles does it take to infringe a patent?

David Knight


United Kingdom

We have reported previously on the impact of numerical limitations in patent claims and on the law of equivalents following the Supreme's Court's Actavis decision. The recent judgment of HH Judge Hacon in Regen Lab v Estar Medical brings the two concepts together.

We have reported previously on the impact of numerical limitations in patent claims (here) and on the law of equivalents following the Supreme Court's Actavis v Eli Lilly decision (here).  The recent judgment of HH Judge Hacon (sitting as a deputy High Court Judge) in Regen Lab v Estar Medical [2019] EWHC 63 (Pat) brings the two concepts together. 

The invention 

It is well known that blood can be separated into constituent parts by centrifuging a tube of blood: red blood cells (being the densest) will move to the bottom of the tube, plasma (being the least dense) to the top, leaving in the middle (the so-called 'buffy-layer') white blood cells and platelets.

Regen are the proprietor of a patent for improving this separation (the Patent).  The method claimed in the Patent employs a thixotropic gel.  Such a gel has the characteristic that when it is centrifuged it changes phase from solid to semi-liquid.  This change means that during the centrifuge process it will migrate to a position consonant with its density, relative to the other contents in the tube, and then after centrifuging is complete it will re-solidify thereby providing a robust barrier between layers to prevent re-mixing. 


Estar's product was different to the strict literal wording of Claim 1 of the Patent in two respects:-

  • Claim 1 specified that the thixotropic gel is polyester based - that in Estar's product was not.
  • Claim 1 specified a molarity of 0.10 - the anticoagulant in Estar's product had a molarity of 0.136.

It was necessary therefore to assess whether or not these variants were equivalents that would be regarded as infringements. 

The first issue the judge grappled with is whether multiple differences between the alleged infringement and the claim should be assessed separately or together.  He concluded that they should be treated together:-

"The question is whether the accused product or process is a variant falling within the scope of the claim taking all equivalents into account.   Of course, it will often be convenient to consider equivalents one by one, but there must be a single overall answer in relation to each accused product or process.

As regards so called numerical claims, the judge concluded that they are no different to any other sort of claim, and that the decision in Actavis had not changed that - i.e. one construes the claim, and then applies the tests of equivalence as necessary. 

Reformulated Improver Questions 

As established in Actavis, the so-called Improver questions were reformulated as:-

"The whole approach to interpretation and scope of protection therefore involves the following steps, considered through the eyes of the notional addressee:

  • Does the variant infringe any of the claims as a matter of normal interpretation?
  • If not, does the variant nevertheless infringe because it varies from the invention in a way or ways which is or are immaterial?   This is to be determined by asking these three questions:
  • Notwithstanding that it is not within the literal … meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, i.e. the inventive concept revealed by the patent?
  • Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention?
  • Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?


Of course, in order to establish infringement in a case where there is no infringement as a matter of normal interpretation, a patentee would have to establish that the answer to questions (a) and (b) above is 'yes' and that the answer to question (c) is 'no'.

Applying the above to this case, as regards the first question (same result in the same way), the evidence accepted by the judge was that:-

"… it was of no matter to the exploitation of the inventive concept whether the thixotropic gel was polyester-based or not."

He reached a like conclusion with respect to the differing molarity.   Then, taking the two differences in combination he found that the inventive concept of claim 1 is exploited in substantially the same way to achieve substantially the same result. 

Moving on to the second question (would this have been obvious at the priority date), both sides appeared to accept that the evidence was that if the answer to the first question was 'yes', then the answer to the second question also would be 'yes'. 

As regards the third and final question (was strict compliance nevertheless intended), the submissions and judgment focussed on the requirement that the molarity is 0.10.  Estar submitted that stating the figure to be 0.10 as opposed to 0.1 would lead the skilled person to understand that strict compliance was necessary.  The  judge stated:-

"I accept that the use of the extra decimal place, 0.10M rather than 0.1M, is relevant, although I think it relates to the question whether 0.10M can be stretched to cover 0.136M as a matter of normal construction rather than the question of equivalence.

Regan's position was not that using 0.136M sodium citrate fell within the normal construction of the claim.   Rather, their position was that it did not matter: even if 0.136M was outside the normal construction of claim 1, a 0.136M solution was equivalent to a 0.10M solution.  The judge went on to consider the issue on the question, of equivalence concluding that as there was no clear indication in the patent that strict compliance was necessary, the answer to third question was 'no'. 

Prosecution file 

Finally on the issue of equivalents, as established in Actavis, the court can have regard to the prosecution file where:-

  1. the point at issue is truly unclear if one confines oneself to the specification and claims of the patent, and the contents of the file unambiguously resolve the point, or
  2. it would be contrary to the public interest for the contents of the file to be ignored.

In this case, in order to distinguish over prior art known as Smith, during the prosecution of the patent Regen had asserted:-

"Hence for each tube, a specific combination of a particular tube's material, particular thixotropic gel and particular anticoagulant is claimed. In addition, depending on the tube used, the anticoagulant is to be present in a specific state (solution or anhydrous) and at a specific concentration. … In summary, the primary feature of the processes which distinguishes them from those disclosed in [Smith] is the use of specific tubes."

In this case the judge felt that neither of the above two requirements were satisfied and therefore the prosecution file has no effect on the scope of claim 1. 


Consequently,  the judge concluded that although the Estar's product differed from the strict literal wording of the claim in two respects, these variants were not sufficient to take the product outside the scope of the claim.  Therefore, had the patent been valid it would have been infringed - fortunately for Estar he concluded that the patent was invalid. 

An unusual twist 

Between the trial and the handing down of the judgment, for reasons which are not recorded in the judgment, Estar dispensed with its legal team, appointed a new legal team and brought an application to re-open the trial and introduce new evidence that had been discovered.  That application was dismissed: the reasons are set out in the judgment. 

In such circumstances the court has a discretion to re-open a trial - it can even do so after judgment has been handed down, but before the order has been sealed. 

First the judge disallowed one of Estar's proposed new claims of invalidity on the basis that it could and should have been pleaded before trial.  As regards a second new claim of invalidity, the judge did not accede to the application to re-open because it would make no difference - he had concluded already that the patent was invalid.  This does raise a question what happens if Regen appeal the judgment and overturn the finding of invalidity - in such circumstances the new evidence might become highly pertinent.  The judge's answer to that was that it was open to the Court of Appeal also to overturn his decision not to re-open the trial, in which case the question of validity in light of the new evidence could be remitted back to the High Court for a further hearing.  The judge felt that it was a better to have that possibility rather than the certainty of another one or two days in court to hear evidence and argument on the allegedly newly discovered evidence. 

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