The legal test for inventive step in the UK courts - according to the Windsurfer/Pozzoli approach - involves an assessment of what would have been the common general knowledge (CGK) of the notional skilled person at the priority date of the patent. Once the CGK is decided on, it is combined with disclosures of other prior art document(s) to determine whether or not the invention in question is obvious.

Great importance is placed on CGK in the UK courts, and as such, any re-definition of CGK is likely to have a significant impact on the way in which inventive step is assessed.

In the recent decision handed down in Teva UK Ltd & another v AstraZeneca AB, Mr Justice Sales, called for an adaptation and modernisation of the concept of CGK in line with current procedures for dissemination of scientific knowledge in the age of the Internet and digital databases of journal articles.

Authority on CGK

In General Tire v Firestone, CGK was defined as knowledge which is "generally known and accepted" by those in the art, and is part of their "common stock of knowledge". Laddie J expanded on this definition in Raychem Corp's Patents, stating that CGK is material the skilled person knows exists, would refer to as a matter of course, and would generally regard as sufficiently reliable. In particular, he clarified that "this does not mean that everything on the shelf which is capable of being referred to without difficulty is common general knowledge, nor does it mean that every word in a common text book is either".

Accordingly, until very recently, the view in the UK had been that knowledge must be generally known and accepted as uncontroversial, to form part of the common stock. Caution had been taken by the courts in expanding the scope of CGK, since if the skilled person is deemed to know more, it follows that fewer inventions will be deemed inventive.

Redefinition of CGK: Teva v AstraZeneca

AstraZeneca's patent concerned the second medical use of a known combination of drugs for relief treatment of asthma. The case turned on whether it was obvious from the CGK to use the same combination disclosed in the prior art for relief treatment.

In his judgment, Mr Justice Sales identified three different classes of CGK relevant to the case in question:

  1. Conventional CGK: statements in standard reference texts and a few leading journal articles.
  2. Primary articles: academic articles which "were sufficiently prominent in the main academic journals in the field".
  3. Secondary articles: a range of journal articles "which were not in leading journals" and "would not have been likely to have been read by the notional skilled person in the ordinary course of keeping himself up to date" but "would have been quickly identified by any person conducting a literature search and review".

This third category of CGK appears somewhat incongruous with Laddie J's definition above. Sales went on to explain that such broadening of CGK is necessary because searches on the internet and online databases are now part and parcel of the routine sharing of information in the scientific community and are thus ordinary research technique.

Conclusions from Teva v AstraZeneca

It is now apparent that the relevant CGK of the skilled person will include material that would be readily identified by a search in a database of journal articles or on the Internet.

In light of this decision, the test for whether a piece of information is CGK will likely depend on its ease of access rather than its degree of acceptance in the field. This could have significant bearing on the decision of future cases.

A greater emphasis is placed on the role of CGK in the UK courts as opposed to, eg, at the European Patent Office (EPO) or in the US. Thus, to credit the skilled person with a greater stock of knowledge would arguably mean a fundamental alteration to the test for inventive step, making it a higher hurdle to jump.

Such an expansion of the CGK could weigh significantly against the patentee, and in favour of third parties seeking revocation.

On the other hand, advocates of this decision would argue that information is now so readily available at our fingertips that the very concept of CGK is due a welcome overhaul.

Useful link

The full decision of Teva UK & another v AstraZeneca AB can be read online at