Given the current energy crisis and the pressing need for alternative energy solutions, patent disputes in the energy sector will undoubtedly increase. In one recent dispute in this space, the High Court invalidated one of Siemens Gamesa's patents in relation to offshore wind turbines.

While the decision in Siemens Gamesa Renewable Energy A/S v GE Energy (UK) Limited(1) is of interest to the energy sector, it considered a number of interesting issues that are of wider relevance. This article addresses claim construction, the relevance of the prosecution history and territorial limits to infringement, and the impact of this decision on future disputes in this space.


The defendant, GE Energy (UK) Limited (GE) is undertaking the provision of wind turbines for offshore electricity generation on Dogger Bank. Dogger Bank is claimed to be the site of the world's largest offshore wind farm and is located more than 130 kilometres off the north-east coast of England. Once fully operational, the Dogger Bank Wind Farm will be capable of powering up to 6 million homes.

GE's product is called the "Haliade-X" wind turbine. The offshore wind turbines in issue are no small undertaking, with Meade J describing them as "mighty machines: the blades are of the order of 100 metres long". Siemens alleged that GE had infringed its European patent, which relates to the use of bearings in rotor hubs for wind turbines. GE counterclaimed for invalidity.

Parallel proceedings have also taken place in the United States, where a related patent was found to be valid and infringed, and France.


Meade J held that Siemens's patent was invalid for obviousness over the prior art, but rejected all other invalidity attacks, including the insufficiency allegations.

In respect of infringement, the judge held that neither the fully assembled Haliade-X nor its hub fell within the scope of the relevant claims of the patent (claims 1 and 9). Therefore, there was no infringement on a normal construction (and doctrine of equivalence was not pleaded).

However, he noted that one of the claims, claim 9, would have been infringed by GE's acts in relation to the Haliade-X rotor hub in mainland United Kingdom had the patent been valid.

He also found that Dogger Bank, which was the only site of an allegedly infringing act at which the Haliade-X would be fully assembled, is not within the territorial ambit of the Patents Act 1977, so GE's acts in respect of that site were not infringing acts.

An argument was raised as to whether the unassembled components of the Haliade-X in the United Kingdom infringed on the basis of a "kit of parts" argument. However, the judge concluded that he did not need to decide this issue based on his overall findings.

Claim construction
The disputed issues on claim scope in this case all concerned the "normal" interpretation of the claims, and there was no issue about infringement under the doctrine of equivalence. In this respect, the judge's comments on claim construction provide useful guidance in respect of the purposive approach to be taken in construing a claim on the normal interpretation. The judge in this case indicated that it is permissible for a patentee to rely upon how an invention works or what the particular invention is trying to accomplish.

In particular, the judge said at [63]:

Infringement by equivalence now has to be pleaded in patent cases. This is a salutary and useful practice, but it has led to it being common for the alleged infringer to make objections, where equivalence is not pleaded, that the patentee is limited in what can be argued in support of "normal" interpretation. This happens in particular where the patentee seeks to rely on how the invention works and what it is trying to accomplish. These objections are generally misconceived, in my view. "Normal" interpretation includes purposive matters of this kind. Equivalence arises on top of normal interpretation and that is what has to be pleaded. Thus in the present case GE argued, at least at one stage, that Siemens' arguments about how press-fitting works were not allowed because they were unpleaded. I do not agree (and the objection faded rather) – the issue was "normal" interpretation of a general word in context. Siemens was not running equivalence.

As such, the Court will not prevent a party from relying on the workings of an invention or its desired purpose when construing the claim language. The Court will intervene in circumstances where there is no issue of general claim construction on a normal basis and a party is seeking to rely upon equivalence arguments without having properly pleaded or particularised such a claim.

Prosecution history
In the United Kingdom, reliance on the prosecution history of a patent to determine the extent of protection or scope of a patent can be made in only very limited circumstances, following the Supreme Court's decision in in Actavis v Lilly.(2)

So far, while it has been argued in a number of cases, the UK courts have been reluctant to consider the prosecution file history. In the present case, reliance on the prosecution history arose in the context of construing the relevant claims and in particular in relation to the use of the word "integral" (in claim 1(d) "integral with an annular member of the rotor hub" and in claim 9(d) "at least one annular member integral part of a bearing").

In construing the meaning of the word integral, Meade J noted that the "ordinary usage can extend to that which is an undivided whole (GE's contention, essentially), or to something made up of components which form a unity (closer to Siemens' position)".

The judge also found that, in the context of the prosecution file, the word "'integral' would be understood to be a more stringent requirement than merely 'firmly connected' and would not cover bolted connections".

Meade J reviewed Actavis v Lilly, and noted that it would be appropriate for a Court to consider the prosecution file in two circumstances – namely, if:

  • the file clearly and unambiguously resolves the point of construction in issue; or
  • it would be contrary to the public interest to ignore it.

He noted that "one expects that [these circumstances] will only rarely arise and that the conditions for them to do so will be stringent". In particular, in respect of the first point, he said that: "The first requirement will not be met merely because some point of interpretation is arguable both ways in the context of the specification; that happens all the time. More is needed." In respect of the second point:

The second requires that the file provides a clear answer, and will not be met just because the file says something that might be relevant. It is not legitimate to promote the file into a sort of adjunct to the specification and of equal value with it.

He recorded that Siemens's counsel had accepted that the file history can be relevant to both infringement by equivalence and normal, purposive infringement.

In the case in issue, Meade J found that the claims in issue were not sufficiently unclear and that the arguments over the meaning of "integral" could be resolved in the usual way. However, he found that even if he was wrong, in his view, the file did not unambiguously resolve the matter, and rejected GE's reliance on the file history.

The judge found that, when fully assembled, the Haliade-X did not have all the features of claim 1, so there was no infringement of that claim.

The judge noted that had he found claim 1 to be infringed, Siemens still would have faced the problem that the Haliade-X was never fully assembled until put in place on Dogger Bank.

Further, Siemens argued that having all the parts of the Haliade-X at the dock in the United Kingdom (within the United Kingdom's territorial scope), but not assembled, infringed claim 1 of the patent by virtue of being a "kit of parts". In the result, the judge declined to decide the issue on the basis that the "point [was] not necessary to the outcome of this action" as, among other things, the patent was invalid.

Siemens also failed on infringement in respect of claim 9 in that the GE product's rotor hub did not fall within the claim.

One particularly interesting aspect of this decision relates to the territorial scope of the Patents Act 1977. The fact that Dogger Bank is the only site of an allegedly infringing act at which the Haliade-X was to be fully assembled required the judge to consider whether the location fell within the territorial scope of the Act.

Section 132(4) of the Act provides that it:

applies to acts done in an area designated by order under section 1(7) of the Continental Shelf Act 1964, or specified by Order under section 10(8) of the Petroleum Act 1998 in connection with any activity falling within section 11(2) of that Act, as it applies to acts done in the United Kingdom.

The judge therefore construed section 11(2)(a) of the Petroleum Act 1998 to consider whether the relevant activities to be done by GE at Dogger Bank in respect of the Haliade-X turbines when their towers are installed on the seabed are "activities connected with the exploration of, or the exploitation of the natural resources of, the shore or bed of waters to which this section applies or the subsoil beneath it", and found that the words of that section should be given their ordinary meaning. This led him to conclude that GE's acts at Dogger Bank would not be "exploitation" of the kind required as the acts did not relate to the shore or bed of waters, and no "natural resources" would be exploited.

In reaching his conclusion, the judge said that:

What is taken advantage of is the mere existence of the sea bed and subsoil beneath it. It does not make sense to say that the resource of some rock is just that it is rock. One can of course understand that taking living or non-living resources like hydrocarbons or seaweed and doing something with them is "exploitation", but drilling out some rock and doing nothing with it is not, in my view.

The judge therefore held that Dogger Bank is not within the territorial ambit of the Act, so any acts undertaken by GE there would not be infringements under the Act.


As the race towards "net zero" fans a boom in investment in renewable energy, it is likely that patent infringement claims concerning "green technologies" will increasingly be brought by industry competitors in respect of each other's patent portfolios.

Indeed, this decision has received much attention by industry press. Despite a different conclusion being reached in the related US proceedings, both decisions bring to the fore complex territorial issues in respect of rapidly evolving offshore wind farms. The present case emphasises the importance of identifying where and what relevant acts of alleged infringement are said to be occurring (or threatened) and ascertaining how those acts are said to fall within the ambit of the Act or what the appropriate forum for a dispute may otherwise be. It is likely that more arguments will run to this effect in the renewable energy sector given the locations of such projects and the relevant activities undertaken.

Of broader relevance is the judge's acceptance that reliance on the prosecution file in patent disputes in the United Kingdom can be relevant to infringement under the normal interpretation in addition to infringement by equivalence, while noting that reliance on the file should be relatively rare and subject to stringent conditions. This means that while the file history may be helpful and potentially informative, it cannot be relied upon for claim interpretation purposes unless it is unequivocal, or it is otherwise in the interests of justice to do so.

It is expected that Siemens will appeal the decision but an appeal is unlikely to be heard until the end of 2023 or even 2024. This, a likely appeal in the US proceedings and a further related UK action listed for trial later in 2023 in relation to which GE is suing Siemens for patent infringement, means that the industry is facing uncertainty in respect of the use of offshore wind turbines. In the light of the global energy crisis, with high costs and the ever-increasing risks posed by climate change, this has led industry commentators to suggest that a commercial resolution may be advisable. However, the potential rewards associated with successful alternative energy solutions may mean that this dispute will continue for some time yet.

For further information on this topic please contact Sarah Taylor or Anna Harley at Pinsent Masons by telephone (+44 20 7418 8250) or email ([email protected] or [email protected]). The Pinsent Masons website can be accessed at


(1) [2022] EWHC 3034 (Pat).

(2) [2017] UKSC 48.