[GuestPost] Lord Justice Birss deals with the kitchen sink and the Formstein defence in Facebook v Voxer

The AmeriKat looking towards
a future of the Formstein
defence from her own
kitchen sink
Is Instagram Live actually live? This is one of the issues
in the case Facebook v Voxer [2021] EWHC 1377 (Pat). Voxer argued that a live broadcast feature offered by Facebook infringes its patent EP 2 393 259. Facebook initiated the present proceeding to revoke the patent. Voxer counter argued that the patent was valid and infringed. The judgment of the pre-trial review had been handed down in March: [2021] EWHC 657 (Pat). The present case has been tried under the Shorter Trials Scheme (a topic for another post, says Merpel....).  

Brussels-based trainee patent attorney, Henry Yang, summarizes the key points.  Over to Henry:


To start, it is convenient to copy the unconditionally amended claim 1 ([69]) below, which was the focus of this case:

1a A media communication method,
1b which supports a live communication mode
1c and at least one time-shifted communication mode,
1d for communicating both voice and video media
1e on a first communication device (13)
1f over a communication network (14),
1g progressively encoding, progressively and persistently storing on the first communication device (13) and progressively transmitting media of an outgoing message originated on the first communication device over the communication network, as the media is created; and
1h progressively receiving, progressively and persistently storing on the first communication device (13) and progressively rendering media of an incoming message received over the communication network at the first communication device as the media is progressively received in a real-time rendering mode,
1i wherein the outgoing message and the incoming message are asynchronous messages (such that the media of an incoming message may be time-shifted with respect to the media of the outgoing message)
1j that are transmitted over the communication network from the first communication device to the second communication device and received over the communication network at the first communication device from the second communication device without first establishing a connection over the communication network between the first communication device and the second communication device
1k and wherein the outgoing message and the incoming message are stored and transmitted at each hop along a path over the communication network.

Facebook raised a comprehensive series of objections: there were disputes on the scope, clarity of the amendments, added matter, obviousness, and sufficiency. Infringement was also under dispute: the issue was whether the unconditionally amended claim 1 was infringed by a live broadcast feature run on the Facebook website, and the Facebook and Instagram Apps on iOS devices.

Claim construction

Live communication mode (1b) and time-shifted communication mode (1c)

Facebook based the interpretation of time-shifting on the glossary in the specification, and argued that it only meant a delay caused by a user choosing to play a message later than the moment when it was received ([74]). Birss LJ, sitting in the High Court, declined to accept this interpretation, based on four reasons: the natural meaning of the words, the fact that the specification mentioned a communication mode where the delay is caused by the network instead of the user, the glossary is not intended to be limiting ([74]), and that it sometimes contradicts reality ([76]): a delay unknown to but actually caused by the user is live from the user’s perspective; a delay not caused by the user is still normally regarded as a delay.

The Judge believed the difference between the live mode and the time-shifted mode was only a matter of degree ([77]).

‘Persistently storing on the first communication device’ (1g)

The Judge declined to accept that ‘persistent storage’ was a term of the art. He held that to satisfy this word, the message not only needed to be stored in a non-volatile medium but able to be retrieved later as well ([94]). Thus storage in a buffer or a temporary store does not satisfy this word.

‘asynchronous messages’ (1i)

The Judge did not agree that the requirement here that messages are asynchronous was inconsistent with the requirement for a live mode, since the term ‘asynchronous messages’ merely meant a message whose timing can be varied ([99]).

‘that are transmitted over the communication network from the first communication device to the second communication device and received over the communication network at the first communication device from the second communication device without first establishing a connection over the communication network between the first communication device and the second communication device’ (1j)

The Judge illustrated this feature, the meaning of which may not be immediately obvious, by the experience of sending a text on a phone ([107]).

‘and wherein the outgoing message and the incoming message are stored and transmitted at each hop along a path over the communication network’ (1k)

The issue here was whether a server which does not have any storage is still a hop ([111]). The Judge held that this feature was to be construed as a skilled person would understand it. Here, the skilled person would understand that storage capacity is required for each hop ([112]).

Clarity of the amendments

On this issue, the law is that lack of clarity introduced by an amendment is a reason to refuse that amendment ([118]). Having had dealt with the construction of claim 1, the Judge noted that the amended claim 1 did not lack clarity ([113]), and the issue turned on claims 2 – 5.

The term ‘near synchronous’ in the amended claim 2 was held to describe a delay which was perceived but small, and was considered to be clear ([120]). In the amended claim 3, the requirements that the messages are near synchronous and that the method supports a time-shifted mode are consistent, since claim 3 refers to rendering messages live but playing them again later in a time-shifted mode ([122]). The difference between not near synchronous in claim 4 and asynchronous in claim 1 was also held to be consistent, for an asynchronous message in claim 1 meant a message able to be time-shifted (see [99]) and did not concern the actual timing of a message, while claim 4 refers to the actual timing ([124]). The word ‘seamless’ in claim 5 was argued to be unclear ([126]), but the Judge considered that a skilled person could understand that this word refers to the system’s objective ability to provide a seamless quality rather than from a subjective perspective ([132]).

Added matter

‘which supports… at least one time-shifted communication mode…’ in claim 1

Facebook contended that the application as filed only disclosed one time-shifted mode ([139]), but the Judge noted that the glossary in the specification disclosed different things a user could do which corresponded to different modes of time-shifting ([140]).

‘asynchronous messages (such that the media of an incoming message may be time-shifted with respect to the media of the outgoing message)’ in claim 1

Facebook argued that the explanatory rider in brackets was added matter, but the Judge found that it was in [0095] of the application as filed. This rider also confirmed that an asynchronous message refers to a capability of the message, not if it has actually been time-shifted ([142]).

‘wherein the outgoing message and the incoming message are stored and transmitted at each hop along a path over the communication network’ in claim 1

The Judge held that information in this amendment was disclosed in [0151] of the application as filed ([143]). Facebook raised another point that contrary to the original application, the amendment suggested the storage did not need to be persistent, but the Judge held that the storage here referred to the same persistent storage as in the application and as the features 1g and 1h ([144]).

Claim 3 as a whole

The Judge considered that the idea of claim 3 is part of the general disclosure of the application as filed ([145]). The Judge also considered that the specification teaches that the method can both render media from storage in a time-shifted mode and render it in real-time ([146]). So there is no added matter in claim 3.

‘seamlessly transition between the live communication mode and the time-shifted communication mode’ in claim 5

Facebook contended that the amendment made it possible that the transition was between separate conversations, but the Judge held that the seamless transition only made sense if it happened in the same conversation ([147]).


The alleged infringement took place when a live broadcast feature was run on the Facebook website, and the Facebook and Instagram Apps on iOS devices. These three modes were similar ([149]). The issues concerned a normal construction under s.60(1) of the 1977 Patents Act, equivalents, s.60(2), and the Formstein defence ([168]). There were eight points ([167]), listed under the subsection ‘Infringement under s.60(1)’ below.

Infringement under s.60(1)

i) live communication mode

There was an inevitable transmission delay of around 10 seconds between a broadcaster broadcasting the video and his audience watching it ([161]). The Judge held that this was too long a delay to argue that Facebook’s method in fact supported the live communication mode in claim 1 ([170]). This long delay was the key reason why the Judge rejected in [174] – [176] several arguments from Voxer.

The Judge added that the proper way to consider a conversation was that both parties were communicating with the method, which made the total delay reaching 20 seconds, yet farther from a live communication mode ([171]).

ii) time-shifted communication mode

Due to the 10-second delay and his claim construction (see e.g. [74]), Facebook’s method was a time-shifted communication mode ([177]).

Facebook also tried to argue that the stored ‘was live’ video might be different from the live video which could have had been of a poorer quality due to bandwidth limits, but the Judge held that what mattered was that these two videos would be regarded by the user as the same ([178]).

iii) both voice and video

The Judge held that to satisfy this feature, a method needed to support only combined audio/voice messages ([179]).

iv) persistent storage, outgoing message

The outgoing data was only stored either in the short-term buffer in RAM or as a temporary copy in the tmp directory which was in non-volatile memory. Voxer accepted that storage in the short-term RAM buffer did not satisfy the claim ([180]). The Judge held that storage in the tmp directory did satisfy the requirement of persistently storing an outgoing message ([182]).

Since buffering and caching on a personal computer only occurred in RAM, the Facebook website did not infringe this feature ([183]).

v) persistent storage, incoming message

The issue here was when the incoming message was stored in a temporary cache ([184]). When a user started watching a video again after a pause or rewind, the video would come from the temporary cache. This was held to satisfy this feature ([187]).

vi) incoming and outgoing messages

The Judge appeared to have held that if the inherent 10-second delay had been much shorter, this feature would have been satisfied ([190]).

vii) asynchronous message

The issue here seemed to turn on what an asynchronous message was ([195]). The Judge considered, as the rider in the feature 1i and the specification indicate, it to be a shift of the incoming message relative to the outgoing message, rather than time-shifting in a video within a single incoming message relative to itself ([192]). Against Voxer’s initial submission before trial, Facebook submitted that if the incoming message was unrelated to the outgoing message they could not be asynchronous messages ([191]), but the Judge considered the situation where two users of the Facebook technology used the broadcast feature to exchange videos, in which it was possible to time-shift the content of one message with respect to the other, satisfied this feature ([194]).

viii) stored at each hop

There were servers in the network which did not store the message. Therefore this feature was not satisfied ([198]).

There was as a result no infringement under s.60(1).

Infringement under s.60(2)

On the conclusion reached above this issue did not arise ([200]).


The first point on equivalents was obiter on the ‘disclosed but not claimed’ objection to equivalents ([201]): if an embodiment is disclosed but not claimed, the first Actavis question may be answered in favour of the patentee, but the fact that it is substantially the same with other embodiments but actually not claimed puts the third Actavis question against the patentee. Or the embodiment claimed to be an equivalent actually operates in a materially different way compared with the embodiments covered by the claims and thus the argument for equivalents fails at the first Actavis question already. In either scenario there is no infringement.

The second point from Voxer concerned storage at each hop. All three Actavis questions were answered in Voxer’s favour. On the first question, what was necessary for the invention was held to be that each server (‘hop’) was able to access the message if it so wanted. This could be achieved, as Facebook did, by a distributed server system accessible by all the relevant servers, which achieved substantially the same result in substantially the same way ([203]).

The functional equivalence was considered obvious for a skilled person, placing the second Actavis question in Voxer’s favour ([204]). On the third Actavis question, the Judge found that strict compliance with the requirement ‘at each hop’ was not intended, which meant the third Actavis question should also be answered in Voxer’s favour ([207]).

However, as explained in the subsection ‘Infringement under s.60(1)’ there are other features which were not satisfied under s.60(1) infringement. Since they were not argued under equivalents either, the live broadcast feature of Facebook did not infringe the patent in question.

Formstein defence

Formstein defence is established in German law. It means if a claim lacks novelty or is obvious under the doctrine of equivalents, the claim scope must be limited to its normal construction. The Judge commented in obiter that Formstein would be the right approach for the UK ([216]), and that under Formstein defence Voxer could not depend on equivalents ([217]). This will be discussed in more detail in the final section ‘Comments’.


Obviousness over US 2006/0003740 A1 (Munje)

After giving a summary of relevant information in Munje ([221] – [225]) and pointing out that Munje did not disclose the feature 1d ([227]), or the word ‘persistently’ in the features 1g and 1h ([235] within [228] – [235]), or the feature 1k ([239]), the Judge analysed whether the difference between Munje and claim 1 was obvious.

On the feature 1d, the Judge accepted Facebook’s expert evidence that an implementer of Munje would have been familiar with a 2004 protocol by an organisation called OMA and the future roadmap for that protocol ([244]). Although the 2004 OMA protocol related to a voice system ([32]), the future roadmap comprised the idea of including video in addition to voice ([244]). The Judge also accepted Facebook’s expert evidence that there was no technical difficulty in implementing Munje for video messages ([245]). Hence the feature 1d was obvious.

On the word ‘persistently’ in the features 1g and 1h, the Judge found it obvious to store the messages persistently on a device. This was especially true since Munje suggested keeping a more complete history of the communications ([251]).

For the feature 1k, the Judge again referred to Munje’s suggestion to keep a more complete history of the communications, and considered it obvious to store the messages on the network because first, the mobile devices had limited memory and secondly, this was obvious in a one-to-many system to allow others to access the stored history ([252]).

As such claim 1 was obvious over Munje ([254]), as well as claims 5 and 10 ([254], [255]).

The Judge admitted that his analysis on obviousness over Munje involved several steps, but pointed out that none of these steps involved a problem solved by the patent, which would make that step non-obvious ([257]).

Obviousness over WO 2006/121550 (Atarius)

After an overview of Atarius ([258] – [260]) and mentioning the difficulty in identifying the exact differences between claim 1 and Atarius ([267]), the Judge considered that Atarius did not help with Facebook’s case based on Munje ([268]). Facebook tried to dispute the inventive step over Atarius by starting from instant messaging ([269]). The Judge accepted that incorporating videos into instant messaging did not present difficulties, such that attaching and exchanging pre-recorded video clips was obvious ([269] – [270]). However, progressively transmitting the media of an outgoing message and video conferencing both did require an inventive step ([270]).

Hence claim 1 is not obvious over Atarius.


There were three points on insufficiency, explained in turn below.

i) The term ‘asynchronous messages’ is wholly unclear.

This was insufficiency by uncertainty, which the Judge had already rejected ([275]).

ii) The skilled person is not able to ‘demarcate’ videos into messages.

The experts of Facebook and Voxer agreed that the only way to achieve this demarcation was by providing a user interface such that the user marked the beginning and the end of a video ([277]). Facebook presented this point as a squeeze over the prior art, and the Judge had interpreted the prior art in this way ([278]).

Facebook also submitted that claim 1 was not enabled over its whole breadth. But the Judge declined this submission. He pointed out that Regeneron v Kymab [2020] UKSC 27, the authority relied upon by Facebook which had ruled that a range needed to be enabled across its entire scope, only concerned ranges under the Regeneron sense but not other ranges. He held that the term ‘asynchronous messages’ in claim 1 was not a range under the Regeneron sense, if a range at all ([279]).

iii) A general submission that the patent is no more enabling than the prior art.

The Judge considered that a skilled person would have no difficulty in implementing the video communication systems in the prior art or in the patent ([280]).


The amendments were allowed. But the patent was invalid for obviousness over Munje and not infringed ([283], [284]).


There are three comments in this judgment which merit additional attention. First, in [56] Birss LJ held that there was no special legal principles of claim construction if the specification included a lexicon. As relevant as the definitions were, other factors such as the specification as a whole and the common general knowledge were also important.

Although Birss LJ suggests that the glossary may sometimes be determinative, one thinks these occasions may be rare. Two such situations may be that a revolutionary invention requires a new word to be created, or the specification expressly excludes the interpretation of a word by the common general knowledge. But inventions are more often incremental than revolutionary; patent agents tend to cover a scope as wide as possible rather than exclude other possible interpretations of a word. This means that express definitions given in the specification would be seldom determinative.

Secondly, regarding the prohibition of added matter Facebook submitted that the policy behind was to prevent any difference in the monopoly between what the application originally justified and what the patent eventually obtained, then based on this submission appeared to argue that ‘asynchronous message’ was not in claim 1 as filed, which had made this term added matter ([141]). But the Judge declined this argument. He pointed out that differences between the monopoly originally claimed in the filed application and the one in the granted patent were allowed (which happens often during the prosecution). He explained in [134] that one needed to stick to the law explained in Conversant v Huawei [2020] EWCA Civ 1292, [55] – [60] and apply the comparison in Bonzel v Intervention [1991] RPC 553. 

Thirdly, Birss LJ noted that the Formstein defence has been recognised both in the German system ([212]) where validity and infringement are decided by separate courts, and in the Dutch Court of Appeal which as the UK Patents Court is not bifurcated ([213]). Birss LJ supported the Formstein defence in the UK, for two reasons ([216]): first, if the claim was valid on its normal construction, it appeared harsh to invalidate it based on equivalents. This would promote certainty. Secondly, since several other contracting states to the European Patent Convention recognised the Formstein defence, the UK as another contracting state to the EPC should adopt the same approach as well. In the UK, the Formstein defence was first discussed by Hacon HHJ in Technetix v Teleste [2019] EWHC 126 (IPEC). A formal decision on this issue by the English court, however, no doubt will require more comprehensive submissions from counsel before a more detailed judgment is reached (and it filters it's way up on appeal)."
[GuestPost] Lord Justice Birss deals with the kitchen sink and the Formstein defence in Facebook v Voxer [GuestPost]  Lord Justice Birss deals with the kitchen sink and the Formstein defence in Facebook v Voxer Reviewed by Annsley Merelle Ward on Saturday, June 26, 2021 Rating: 5

1 comment:

  1. For those uneasy about the compulsory use of ViCo for important final trials at the EPO it might be worth noting that in this trial it was the lengthy cross-examination of the opposed experts that was decisive to the outcome of a full-blown trial in which the Judge's attendance was "Remotely, via Teams". Presumably, the technology of the Judge's audio and video feeds were world-class.

    For those in jurisdictions that resolve cases in a bifurcated system, laid out here is a finely-balanced case where both sides thought they should have won, on both the infringement issue and the validity issue, depending on what the claim meant to the judge. In such a context, the passages of this judgement on the use of obviousness/insufficiency "squeeze arguments" are super interesting.

    I can't fault the Judge on his "take" on Formstein. What reasonable mind could disagree? I find it fascinating how English courts decline to grasp the nettle but I suppose it is a bedrock principle of "judicial economy" that you refrain from deciding any legal questions beyond what is strictly needed for the case at hand.


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