Recent experience in the UK Patents Court has shown that the validity of patents for genuine inventions in the telecommunications field will be upheld and infringement found. Patents for merely the obvious will be revoked. In the SSH case, Sony evidently took the view that European Patent (UK) to 2 254 311 (“EP 311”) fell into the latter category. Sony commenced an action seeking revocation in the UK court. EP 311 had a priority date of 1999 and related to an aspect of accessing wide area networks, such as the internet and was particularly concerned with ensuring the Internet Protocol Security protocol suite could be used reliably and securely through a Network Address Translator (intermediate nodes acting as gateways between a private network and e.g. the internet).

Sony’s claim prompted SSH to counterclaim for infringement, alleging that certain Sony Xperia devices infringed EP 311. As is usual in the UK, the claim for revocation and the infringement counterclaim were tried at the same time.

On 10 October 2016, the English Patents Court (Roger Wyand QC, sitting as a Deputy High Court judge) gave judgment in the case. It illustrates two particular aspects of UK patent litigation; (1) amendment during litigation; and (2) the approach to obviousness arguments based on common general knowledge alone.

Amendment during litigation

In the UK, the court has power, in infringement and revocation proceedings, to allow amendments to the patent in suit. The patentee thus has the opportunity, subject to the usual principles about basis and clarity, of seeking to frame a revised claim that, on the one hand, better distinguishes the invention from the prior art but, on the other, still catches the alleged infringement. The amendments can be either conditional (i.e. the patentee intends to defend the claims as granted) or unconditional. The allowability of the amendments (whether or not they add matter, are clear and/or cure any invalidity) will be decided at the same time as the main trial. In the case of amendments that involve a rewriting of the claims (e.g. an insertion of wording from the description), it is important from the patentee’s perspective that proposed amendments are tabled in a timely manner and it is not left too late.

Here, SSH put forward three sets of conditional amendments in the proceedings, the first introducing limitation into all the claims that corresponded with these specific embodiment of EP 311, the second adding an extra limitation into claim 3 and the third a yet further limitation into claim 6. Although points on added matter and lack of clarity were taken by Sony on the proposed amendments, the Judge disagreed on those aspects.

Obviousness and Common general knowledge alone

The case reinforces a recent theme that arguments of invalidity based on common general knowledge alone tend can have difficulties, at least when compared with an attack based on a specific prior art citation. In a previous case, the Court of Appeal has explained that the difficulty arises from the fact that the starting point for the obviousness attack based on common general knowledge alone is not “encumbered with inconvenient details of the kind found in documentary disclosures, such as misleading directions or distracting context”, and pointed out, therefore, that is “vitally important to make sure that the whole picture presented by the common general knowledge is considered, and not a partial one” (Ratiopharm v Napp [2009] RPC 11 at 158).

Indeed, in the SSH case, the Deputy Judge referred to that guidance of the Court of Appeal and, on the facts, rejected Sony’s obviousness case based on common general knowledge alone.

The conclusion was, however, different when it came to considering the obviousness attack based on two particular prior art citations. Originally Sony pleaded six specific items of prior art (apart from the common general knowledge alone case), which is quite numerous by usual UK procedural standards. In the end, Sony limited the number of items of prior art relied upon to just two: firstly, minutes of the meeting of the 43rd IETF NAT Working Group in Orlando of 9 December 1998; and secondly, a document by Senie called ‘NAT Friendly Application Design Guidelines’. The Deputy Judge considered the expert evidence as to the teaching of the cited items of prior art and what the notional skilled person would have understood from them. He concluded that the difference between the cited prior and the invention claimed in claim 1 of EP 311 were obvious steps to the skilled addressee. The subsidiary claims, said by SSH to be valid independently of claim 1, were also all found to be obvious. Nor, in the Deputy Judge’s view, did any of the proposed amended claims cure the invalidity of EP 311.


So far as infringement was concerned, the Deputy Judge held that the Sony Xperia devices would have infringed several of the claims if they were valid in their un-amended form and in their proposed amended forms. However, the infringement claim could not succeed as all the claims of EP 311 (both as granted and as proposed to be amended) were found to be invalid.