• Home
  • Latest
  • A new UK defence to patent infringement? Not quite yet…

A new UK defence to patent infringement? Not quite yet…

Posted on 21 February 2019 by Ben Levy

A new UK defence to patent infringement? Not quite yet…

In a recent decision in the Intellectual Property Enterprise Court (Technetix B.V. v Teleste Limited), HHJ Hacon might have opened the door to a new so-called 'Formstein' defence to patent infringement. Admittedly, the judge's comments were obiter dicta (comments of a non-binding nature) – since the patent in suit was held invalid for want of both novelty and inventive step – but the decision sets up the opportunity to apply this novel defence in future actions.


The UK Supreme Court's decision in Actavis v Eli Lilly introduced, in essence, a doctrine of equivalents, long a part of German and other patent laws, into UK law. Quite how this new approach to claim construction would develop has been a matter of debate ever since the Supreme Court's ruling. Of particular relevance to the Technetix case was the question of how the Court would view an infringement claim based on equivalents, in a situation where the allegedly infringing equivalent was obvious (and therefore not patentable) at the filing date of the patent in suit.

The Patent

Technetix's patent UK 2,382,473 relates to the ability to alter the strength of a cable TV or internet signal that is sent from a point of origin to a 'distribution point' (usually a street cabinet) and which attenuates according to the distance it has to travel and the quality of the cables through which it travels. The signal is then sent from the cabinet onto the set top box in subscribers' homes, causing yet further attenuation. The Patent discloses a cable tap unit with at least one removable directional coupler in the signal path between the input of the signal from the network and a group of signal outputs, such that an engineer will be able to select a directional coupler (small and inexpensive) that is appropriate to the level of output that is required without having to disturb other components.


Claim 1 of the Patent was held invalid for lack of novelty and inventive step over two pieces of prior art, Rocci and Toner. Technetix argued that the invention was not enabled by the prior art since it did not disclose the removal and replacement of a directional coupler "without physically affecting any of the signal outputs". According to the judge's construction of this claim, and unfortunately for Technetix, neither did Claim 1.

Technetix's position was that the judge should construe Claim 1 so as to avoid the obstacles posed by the state of the art, even where such art is not specifically acknowledged in the patent specification. HHJ Hacon rejected this out of hand, instead favouring the rules of construction laid down by the Supreme Court in Actavis v Lilly, stating: "It seems to me that there is no rule that a court must always be slow at finding that a claim lacks novelty over the common general knowledge. It will depend in part on the clarity of the meaning of the claim on a normal construction."

Infringement – a Formstein defence in the making?

Although the judge concluded that the Patent was invalid, he also considered infringement and, in particular, how the expanded scope of claim protection afforded by the relatively newly adopted UK doctrine of equivalents could impact infringement analyses.

Teleste's position was one that has been tried and tested in Germany - the 'Formstein' defence from Case X ZR 28/25 Formstein GRUR 1986, 803 i.e., even if its product fell within the scope of Claim 1, it would do so only as an equivalent, and that there should be a defence to infringement  because that equivalent lacked novelty or an inventive step over the prior art. US patent law also addresses this issue with its principle of 'ensnarement' which prevents the range of equivalents from being so extended that it includes the prior art.

Whilst acknowledging that no standalone defence of this nature exists in the UK, the judge stated that it has long been a basic principle of UK patent law that a patentee cannot prevent a person from doing what he or she has been lawfully entitled to do before the grant of any asserted patent. As support for his position, the judge referred to the cases of Merrell Dow Pharmaceutical Inc v H. N. Norton & Co Ltd and Gillette Safety Razer Co v Anglo-American Trading Co.

HHJ Hacon explicitly acknowledged that English law might adopt a 'Formstein' defence in the future. Not only did he proceed to analyse Teleste's alleged infringement on the basis that such a defence already exists, he found that, if it did, Teleste would be entitled to it.


The introduction of a 'Formstein' defence into English law might be viewed as the natural rebalancing of the basic principles of UK patent law in the light of the significant expansion of the scope of claim protection afforded by the Supreme Court's adoption of a doctrine of equivalents, a protection which is being increasingly exploited by patentees. Perhaps it is only fair that in a world where patentees can assert their patents against a wider audience and a greater number of products, that audience should be entitled to a defence which, at least on the face of it, is contained wholly within the existing patent law canon. Whilst Technetix's patent was held invalid and so the judge did not need to reach a firm conclusion on the point, it is only a matter of time before another party argues this defence in relation to a valid patent. HHJ Hacon appears to have made clear that the adoption of such a defence has his (albeit non-binding) support.

How can we help you?

How can we help you?

Subscribe: I'd like to keep in touch

If your enquiry is urgent please call +44 20 3321 7000

Crisis Hotline

COVID-19 Enquiry

I'm a client

I'm looking for advice

Something else