In a landmark judgment the Supreme Court has rewritten the rules on how patents are to be interpreted. The new world is great news for patent lawyers but not necessarily for their clients.

The Old World

Since section 6 of the Statute of Monopolies came into force on 25 May 1624, it has been possible for inventors to lawfully obtain patents in the UK giving them a limited duration monopoly over certain types of new products or processes.

But how to define that monopoly? In a conveyance or lease of land the area from which strangers are forbidden is easily marked (usually in red) on a plan: step over that line without lawful reason and you become a trespasser. In the “integer space” with which patents are concerned – the integers being the elements of the invention – inventors and their patent attorneys have nothing as clear as a red line. They must use words. Arguments can be had about what those words mean and such arguments are at the heart of most patent actions.

Before the House of Lords decision in Catnic Components v Hill & Smith in 1982, English courts took a twin track approach: firstly the literal meaning of the claims had to be considered to determine whether or not there was so called “textual infringement”. However the red line did not stop there: outside of textual infringement there was a penumbra of often very uncertain width where a third party could still infringe by taking the “pith and marrow” of the disclosed invention.

In Catnic, the House of Lords said this approach was all wrong. There weren’t two causes of action for patent infringement but only one and that one was to be determined by ascertaining what the patentee’s purpose was in using the words he had used. The key question that needed to be asked was whether the patentee had intended to limit his monopoly by reference to a particular integer or not, in which latter case a variant on that integer might still infringe.

To determine what was essential and what was not the court in Catnic proposed a three stage test, which was subsequently rephrased in the 1990 case of Improver Corporation v Remington Consumer Products thus:

(1) Does the variant have a material effect upon the way the invention works? If yes, the variant is outside the claim. If no:-

(2) Would this (i.e. that the variant had no material effect) have been obvious at the date of publication of the patent to a reader skilled in the art? If no, the variant is outside the claim. If yes –

(3) Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention? If yes, the variant is outside the claim.

That purposive approach to construction, determined by reference to the three Improver questions (as they had become known), was then routinely applied by English courts until the Supreme Court’s 2005 decision in Kirin-Amgen.

In Kirin-Amgen Lord Justice Hoffmann reaffirmed that purposive construction required the court to determine what the person skilled in the art would have understood the patentee to be using the language of the claim to mean, but indicated that the Improver questions were no more than guidelines (unhelpful in some cases) – a structured approach – to determine what that correct purposive construction should be. In essence following Kirin-Amgen, there was no “equivalents penumbra” but a single red line, the position of which could be located without any reference to the Improver questions.

Actavis

Actavis was a case concerning a patent which claimed a sodium salt of an organic anion (pemetrexed). Actavis, the alleged infringer, argued that they didn’t infringe because their pemetrexed anion was not linked to sodium but to other cations. Sadly for Actavis the Supreme Court didn’t agree with them.

The court held that the issue of construction of a patent claim is not the same as the issue of determining the scope of protection of a patent claim: rather the two issues are distinct. Construction still requires working out what a man skilled in the art would have understood the patentee to be using the language of the claim to mean. This is an objective process akin to contractual interpretation.

However determining the scope of protection requires a wholly separate analysis, which should involve applying a modified version of the three Improver questions. The modified Improver questions are now:-

(1) 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?

(2) 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?

(3) 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?

Consequences

Following Actavis it is now clear that the scope of protection of a patent claim can extend well beyond what the words of the claim properly construed actually mean: “straight” can mean “bent” as long as “bent” passes the reformulated Improver test.

This is going to create substantial uncertainty for those involved in advising their clients about infringement concerns. What, for example, is the inventive concept in reformulated question (1) and how does one identify it?

The reformulated Improver test may be easier for patentees to succeed on (and thus establish infringement) because they will no longer have to show that the fact that a variant had no material effect on the way the invention works would have been obvious to the man skilled in the art but only that it would have been obvious to such a man, imputed to know that the variant achieves substantially the same result as the invention, that the variant does so in substantially the same way as the invention.

Actavis is bound to encourage patentees to have a go at what prior to 12 July 2017 would have looked like speculative claims to many seasoned professionals; the patentee clearly now has two bites of the cherry.

Some may say with considerable force that the law has gone back to where it was prior to Catnic: although the language used is now different, there appears to have been a return to two separate types of infringement: “textual infringement” and “infringement of the pith and marrow of the invention”, of the very type which the Supreme Court rejected in 1982.

Before patentees get too excited about all this they might want to think about the effect of Actavis on validity. It is a basic tenet of patent law that that which infringes after grant, if made available to the public before the application is filed, will anticipate the patent and render it invalid. This is the basis of the so-called Gillette defence: “that ‘the alleged infringement was not novel at the date of the plaintiff’s letters patent,’ is a good defence in law”.

Historically a defendant who has wanted to establish anticipation has had to show that the prior art relied on fully discloses the claimed invention: “A signpost, however clear, upon the road to the patentee’s invention will not suffice. The prior inventor must be clearly shown to have planted his flag at the precise destination before the patentee” (General Tire & Rubber Co v Firestone Tyre & Rubber Co Limited [1972]).

But now, applying Actavis as signpost, satisfying the modified Improver three stage test should be sufficient to invalidate a patent.

Defendants in patent actions may yet have the last laugh.