Michael Washbrook


Read More

Michael Washbrook


Read More

2 May 2019

TQ Delta v ZyXEL – an obvious problem and the skilled person's attributes

On 11 March 2019, Mr Justice Henry Carr handed down his judgment in TQ Delta v ZyXEL [2019] EWHC 562. The judgment concerns infringement and validity of two patents owned by TQ Delta that are said to be essential to standards relating to Digital Subscriber Line ("DSL") technology. DSL technologies are those commonly used to provide fixed line broadband internet. Two further recent judgments concerning the next steps in these proceedings are discussed later in another Transceiver article.

Background to the dispute

The underlying dispute concerns complaints from TQ Delta that it has been trying to license its SEP portfolio to ZyXEL on a Reasonable And Non-Discriminatory ("RAND") basis without success since 2013. TQ Delta allege that ZyXEL is pursuing a "hold out" strategy, where a potential licensee postpones for as long as possible any payment to the SEP owner to exhaust the SEP owner's resources and will.

The judgment

The judgment in relation to EP 1 792 430 ("EP 430") raises interesting points with regard to the possibility of an inventive problem with an obvious solution leading to a valid patent, and the ability of the skilled person to assimilate complex documents.

Assimilation of complex documents

As is quite common in cases relating to standard essential patents, the cited prior art relied on for the lack of inventive step was an earlier standard, in this case the ADSL2/02 standard. Carr J noted that the ADSL2/02 standard is a comprehensive document running to 312 pages, which sets out a complete specification for every standardised aspect of an ADSL2 transceiver and it was far too long to summarise in the judgment.

TQ Delta submitted that the law requires that the skilled person's real life attributes be taken into account, but ZyXEL's approach was to treat the skilled addressee as having exceptional powers of assimilation and the ability to read massively long and complex documents, retain all of the detail and link the disclosure from one part to all other parts.

Carr J distinguished between hindsight "cherry-picking" from the prior art and the assimilation of the contents of long and complex documents cited as prior art, noting that the former is impermissible, but the latter is not. Citing well-settled case law on this point, he noted that the skilled person is deemed to read and assimilate a prior art document with interest, and it is a separate question whether he or she concludes the document is relevant.

Carr J held that although the prior art was a very long document which was concerned with the entire implementation of ADSL2, EP 430 is only concerned with the limited issue of error reporting and management, and this was a known field at the priority date.

He accepted ZyXEL's submission that the skilled person to whom EP 430 was addressed would have been specifically interested in the impact of ADSL2 on error reporting and management. As is clear from the remainder of the judgment, this would have enabled the skilled person to identify the problem from the ADSL2 standard in the manner advanced by ZyXEL.

An inventive problem with an obvious solution?

Unusually, TQ Delta accepted that once the problem addressed by EP 430 is known, the claimed solution is obvious. However, TQ Delta contended that invention lay in perceiving the problem at the priority date.

Carr J noted that counsel had been unable to point to any case where a patent whose solution was obvious was nonetheless held to be inventive on the basis of perception of the problem. Notwithstanding this, he recognised that such a case is possible and that it had been noted by the Technical Boards of Appeal ("TBA") in the European Patent Office that the identification of a technical problem could give rise to an invention.

However, Carr did state that while he agreed with comments in the case law of the TBA, in a field where the skilled person regularly confronts technical problems and is used to solving them, if a real problem exists, she or he is likely to be aware of this.

In the present case, Carr J held that there was no invention. It appears that, importantly, TQ Delta was unable to demonstrate that there was any period of long felt want, ie evidence of a longstanding problem that had not previously been perceived. Carr J found that the problem would have been apparent at the priority date.

EP 430 was therefore held to be invalid. However, the other patent in this case, EP 1 453 268, was held to valid and infringed.


On the assimilation of complex documents, it is not surprising, considering the settled case law that Carr J noted that there is a distinction between the skilled person reading a document with interest, and considering its relevance. For the purposes of telecoms cases, where prior art can run into hundreds of pages, this is a sensible approach.

The circumstances in which an inventive step can be based on perception of a problem are likely to be uncommon. It appears that the patentee may need to demonstrate that the problem is both longstanding and had not been previously perceived.

Call To Action Arrow Image

Latest insights in your inbox

Subscribe to newsletters on topics relevant to you.


Related Insights

Information technology

TQ Delta v ZyXEL – ZyXEL found to have engaged in "hold-out" and injuncted in advance of RAND trial

2 May 2019

by Michael Washbrook

Click here to find out more