On 12 July, the English Supreme Court introduced a major change to English patent law, extending the potential scope of protection of a patent beyond the interpretation of its claims to variants which achieve substantially the same result in substantially the same way as the invention of the patent.

The case (Actavis v Eli Lilly1) has serious implications for businesses in all industry sectors, not just the pharmaceutical sector. It will now be much easier to establish a variant of a product or process that directly infringes a patent. By making the courts more patent-friendly, this may well lead to an increase in patent litigation in the UK. Extending the scope of protection in this way also makes it more challenging for implementers to judge whether or not a particular product or process infringes a patent, and design around it.

We recommend clients look again at their freedom to operate assessments in the UK and re-evaluate the possibility of achieving their business goals by litigating in the UK.

The background

The essence of Eli Lilly's invention was the discovery that the damaging side effects of pemetrexed in treating cancer could largely be avoided by administering pemetrexed disodium together with vitamin B12. As a matter of ordinary language, the claims clearly only extended to the use of pemetrexed disodium (they specifically claimed its use). However, notwithstanding that, the Supreme Court held that Actavis's product, which contained pemetrexed diacid or a pemetrexed salt other than pemetrexed disodium (i.e. not pemetrexed disodium), directly infringed the patent.

The change

The extent of the protection conferred by a European patent is determined by its claims2. However, the Protocol on Interpretation provides "due account shall be taken of any element which is equivalent to an element specified in the claims"3.

Until this decision, the sole question under English law what the person skilled in the art would have understood the patentee to be using the language of the claim to mean. The language chosen was usually of critical importance. The courts rejected applying a "doctrine of equivalence", being concerned that, "once the monopoly had been allowed to escape from the terms of the claims, it is not easy to know where its limits should be drawn"4.

However, the Supreme Court held that two questions had to be answered in order to give effect to the Protocol on Interpretation: (1) does the variant infringe a claim as a matter of normal interpretation; and, (2) does the variant nonetheless infringe a claim because it varies from the invention in an immaterial way? The latter extends the potential scope of protection of a claim, introducing a doctrine of equivalence test for the first time. It raises questions that the court will normally have to answer by reference to the facts and expert evidence.

What is an immaterial variant?

To answer question (2), the Supreme Court applied the following test (modifying the "Improver" questions):

  • Does the variant achieve substantially the same result in substantially the same way as the inventive concept revealed by the patent? If yes:
  • 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? If yes:
  • Would such a reader have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the claim of the patent was an essential requirement of the invention?

If the answer to the last question is "no", then non-literal infringement is found.

Application to this case

The Supreme Court held that the skilled addressee would understand that the reason why the claims were limited to the disodium salt was because it was the only pemetrexed salt on which the experiments described in the specification had been carried out. The court further held that, given the common general knowledge, it was highly unlikely that the addressee would have concluded that the patentee could have intended to exclude any pemetrexed salts other than pemetrexed disodium. Hence, the court found Actavis's product to be an immaterial variant and that it infringed the patent through the doctrine of equivalence under English, French, Italian and Spanish law.