The Cooperative Patent Classification System Becomes The Official Patent Classification System At The U.S. And European Patent Offices

by Downs Rachlin Martin PLLC

Just this past January, the U.S. Patent and Trademark Office (USPTO) and the European Patent Office (EPO) each announced the launch of the Cooperative Patent Classification system (CPC) as the official system for classifying patent documents at both patent offices.  In this post, I provide a bit of an introduction to the CPC and the classification systems it has replaced, at least officially.  In a follow-up post, I will examine the implementation of the CPC with the following question in mind:  how successful will it be?


You may be asking yourself – why do I care about this bit of patent esoterica? – and that would be a good question.  The classifying, i.e., indexing, of patent applications and issued patents according to the technical features of their inventions is an important tool. Patent classification systems help patent examiners, researchers, legal professionals, professional searchers, etc., in finding patent documents that may be relevant to a task at hand, such as examining patent claims for patentability, conducting a freedom-to-operate analysis, or performing an invalidity study.  Most people who deal with patents or patent applications, whether inventors, IP managers, or attorneys thus interact with the classification system, even if not directly aware of it.  Having a little bit of extra knowledge about how patents are classified can help, for example, when engaging a searcher or when talking to your attorney about the propriety of a restriction requirement.

Many patent offices around the world have devised patent classification systems for use in their own offices.  For example, the USPTO developed the U.S. Patent Classification system (USPC), the EPO developed the European Classification system (ECLA), and the Japan Patent Office developed the Japanese File Index system (FI).  In addition, to promote uniform classification of patent documents around the world, the International Patent Classification system (IPC) was developed under the Strasbourg Agreement, a treaty administered by the World Intellectual Property Organization (WIPO).

CPC to Harmonize Patent Classification

Almost two-and-a-half years ago, the USPTO and EPO jointly announced a collaborative project to harmonize patent classification between the two offices, and the recent announcements, mentioned above, of the official launches of the CPC at both offices is a major milestone of that project.  Some of the stated goals of the CPC were to:

  • increase search efficiency by eliminating the need to separately search patent documents classified differently under the USPC and the ECLA;
  • leverage strengths of both the USPC and the ECLA;
  • create a classification system consistent with the IPC, which is used by more than 100 patent offices around the world;
  • provide a highly granular classification scheme (the CPC has over 260,000 symbols, while the USPC has around 150,000 and the ECLA has around 140,000) that other patent offices will want to adopt;
  • eliminate the need for the EPO to classify U.S. patent documents under the ECLA;  and
  • provide a collaborative classification scheme.

As of this past January, the CPC replaces the USPC as the official patent classification system at the USPTO, and at the EPO it replaces the ECLA as the official system.

Challenges of Adoption

The CPC is based heavily on the ECLA, which itself is essentially a more granular version of the IPC (~140,000 symbols for the ECLA versus ~69,000 for the IPC).  Because the CPC is based on the EPO’s own ECLA, it would seem logical that the changeover to the CPC at the EPO should be relatively easy.  However, as I will cover more in the next post, the CPC is different enough from the ECLA that it may take a bit longer for searchers to get used to it than the proponents of the change would hope.

The situation at the USPTO, however, could be much different.  The USPC, which is the oldest patent classification system, is not based on the IPC and is vastly different from all three of the CPC, the ECLA, and the IPC.  Consequently, the changeover at the USPTO may be much more challenging.  Indeed, as I will discuss in the next post, the changeover from the USPC to the CPC by USPTO examining corps appears to be slow.

So just what are the differences and why might they slow down adoption?   For one thing, while the CPC, the ECLA, and the IPC share similar organizational schemes, there are important  distinctions.  An example listed at a CPC website provides some insight.  The example there highlights two primary distinctions among the three schemes.  First is the disparity in granularity between the IPC on one hand and the CPC and the ECLA on the other hand.  In that example, for a single IPC symbol, each of the CPC and the ECLA contain nine “sub-symbols” representing additional levels of granularity.  Increased granularity makes searching via the CPC and the ECLA more efficient than searching via the IPC.

The second primary distinction is the difference in symbologies used by the CPC and the ECLA.  For categories located increasingly down a hierarchical chain, the ECLA uses increasingly longer symbols.  For example, under symbol H01L21/027, some hierarchical-chain sub-symbols are H01L21/027B, H01L21/027B6, H01L21/027B6B, and H01L21/027B6B2, with each additional identifier in the chain of symbols indicating an additional level down the hierarchy.  However, the CPC uses fixed-length symbols throughout multiple hierarchical sub-levels.  For example, the CPC symbols corresponding to the forgoing chain of ECLA symbols are H01L21/02709, H01L21/02727, H01L21/02736, and H01L21/02745, respectively.  Thus, searchers readily familiar with the ECLA and used to being able to visually identify locations within a hierarchy at a glance based on the length of a symbol no longer have that convenience under the CPC.

With that introduction, I’m sure you cannot wait for the next post when I will try to bring it all together for you.

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

© Downs Rachlin Martin PLLC | Attorney Advertising

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