Global Cooperation on New Patent Classification


We are running through exciting times when profound changes are taking place in the patent regimes across the world through global cooperation. Much awaited reforms in the US Patent law have taken place recently with the passage of America Invents Act. Most of us are also aware of the ‘Patent Prosecution Highway (PPH)’ that is shaping up the prosecution process of inventions that end up subscribing to patent families across various patent offices with greater ease and speed. Patent classification is yet another arena that stands to witness significant amendments in the near future with intense cooperation between major patent blocks of the world in a very significant way. Some of the ongoing developments in this area are discussed here in this article, duly highlighting what is known as ‘Cooperative Patent Classification (CPC)’, the launch of which early next year is likely to be an epoch making event in the history of patents, especially with regard to searching the patents.

What is Patent Classification

A patent document, when published, either as an application or a granted patent, contains detailed bibliographic information broadly covering title, background, abstract, inventors, assignees, technical description, drawings, claims etc. This bibliographic data by itself is insufficient to throw any light on the technical field of the invention. In order to organize and index the technical nature and scope of invention as described in the patent specification, patent classification schemes are employed. Generally speaking, these schemes are constructed and maintained by and for patent examiners. When examining a patent application, the examiner needs to search a collection of previous patent documents to identify relevant prior-art and to establish the novelty of the patent under consideration. Essentially, therefore, the patent classification schemes are maintained and largely used by the patent granting authorities themselves for their internal use. Nevertheless, since patent data and information is now widely retrieved online for various different uses, anyone who is interested in searching patents requires to be abreast and adept is using patent classification codes. Patent Classification codes as ascribed to each patent are conspicuously discernible on the front page of patent document, i.e., US Class : 424/59, International Patent Class A61K8/00 and so on.

International Patent Classification (IPC) system developed and maintained by World Intellectual Property Organization (WIPO) came into existence since 1968. Today since by far all Patent Offices ascribe appropriate IPC codes to patents under examination in their jurisdiction, besides their own national classification codes, this has eased patent searching through IPC codes from cross-jurisdictional databases a great deal as compared to that in earlier times.

Major Patent Classification Schemes

Classifications, by definition, are groups of patent documents of similar subject matter. All major patent jurisdictions have their own unique patent classification schemes which took shape based on their own specific circumstances and needs. For this reason, there also is no direct relationship between one patent classification schemes with another. Some of the major patent classification systems include United States Patent Classification, International Patent Classification, European Patent Classification (ECLA), German Patent Classification System (DEKLA) and Japanese F-Index and F-terms. Depending on the source of patent databases, the user is therefore required to be well versed with the nuances of the underlying patent classification scheme to extract meaningful data. However, it is expected that this diversity of various classification system would soon vanish with emergence of Common Patent Classification scheme which most jurisdictions would eventually adopt. Till such time, however, it is necessary to know the specific features and characteristics of major patent classification schemes.

United States Patent Classification

The US Patent Classification system was launched in 1836; since then it has expanded many folds. Although it is applicable to US patent documents only, it is one of the most important national patent classification systems. Due to sheer size of the US patent data and its comprehensive coverage to wide range of technical fields with strong economic relevance, it is one of the most widely used system. Presently, the total number of classes in USPC is in excess of 450 and together with sub-classes well over 150,000 which keep growing with successive revision taken up periodically.

US classification system is stated to be a hybrid one based on “functional” aspects of the inventions as well as their “industrial application”. In the classification code, a class is regarded as the major component referring to one technology or subject area, where subclass is a minor component referring to processes, structural and functional features. Every class has a unique alphanumeric identifier, as do most subclasses.

The format of US class is as : CCC/SSS.sss, where the ‘Class’ is represented by the up to 3 digit and the subclass is a number up to 6 digits where the last three digits are decimal places. Subclasses are usually 1 to 3 digit numbers, and subclass numbers with more than one decimal place are rare. Usually, the class and subclass numbers are separated by a slash, although some.

The Index to all US Patent Classes can be accessed by clicking in here with their broad titles. It is worthwhile to browse through these titles to gauge what is beneath these titles. Clicking on the hyper-linked class codes leads to sub-classes at indent and sub-indent levels with their brief titles. It may be noted that there may be several classes for the broad title of the field, e.g., US classes 600, 602, 604 and 606 all refer to the field of ‘surgery’ but their sub-classes are quite different. It is, therefore, necessary to precisely understand which class carries the specific fields of interest.

Getting a knack of the relevant class / subclass that cover the field of interest is therefore very important to be able to retrieve relevant patents from US patent database. Looking through the index of classes and sub-classes of US patents may or may not be readily obvious to determine the relevant class / subclass for the technical field of interest being supported. For example, if one is keen to get all previous patents that deal with ‘wooden door frames’, one would be tempted to look through the Class 144 ‘Wood-working’ and its many sub-classes and can get easily lost without being able to find the relevant class. One easier and often smarter way of getting around such a problem is to look for a few previous patents through key-word search on ‘door frame’. And looking at the patents thus returned, one would find many patents being ascribed US Class 52 ‘Static structures (e.g., buildings). Now looking various sub-classes under the Class 52, one can find the sub-class 204.1 ‘Framing to receive door, door jamb, or window sash’ which seems quite relevant to the original objective of retrieving patents on ‘wooden door frames’. Having figured the relevant Class/Sub-class 52/204.1 as the most relevant, one can at once find as many as 145 patents that carry this US Class. It is also evident easily that another related Class/Sub-class 52/204.5 for ‘Window or window sash, sill, mullion, or glazing’ returns another batch of 121 patents.

The above example shows how one can make use of patent classes for retrieving relevant patents from the concerned database, in this case – US Patent database. Similar techniques can be employed for other patent databases but one needs to fully grasp the applicable patent classification scheme. It may be pointed out here that the diverse array of these patent classification schemes would soon converge to a single common patent classification system the world-over (Please refer to Cooperative Patent Classification described elsewhere in this article).

International Patent Classification

The origin of the International Patent Classification is the “International Classification” created under the ‘European Convention on the International Classification of Patents for Invention’ which was later adopted by the multilateral agreement, known as Strasbourg Agreement of 1971 and finally introduced by World Intellectual Property Organization (WIPO). All contracting states to Strasbourg Agreement and many others assign appropriate IPC codes on patent documents handles by them. Thus, IPC is currently adopted by most Patent jurisdictions.

Offices ascribe IPC codes besides their own codes on all patents granted by them. Another redeeming feature of IPC is that as the old number codes are changed as a result of expansion policy, all old patents residing in various online databases are also updated with new number codes, so that patent search based on a valid IPC code never goes dysfunctional.

The IPC system divides all fields of technology into hierarchical sets of sections, classes, subclasses and groups. Taking the classification down to sub-group level, the there are presently more than 70,000 classes representing various technical areas. The technical areas which may mean any technical matter, e.g., process, product, technique or apparatus are defined and suitably differentiated at the level of a class or a subclass in the International Patent Classification in a patent. It is an indispensable tool for industrial property offices world over, in conducting searches to establish the novelty of an invention, or to determine the state of the art in a particular area of technology. During examination of patent applications, the examiners classify all applications before they are published so that the classification information is available for future searches of novelty.

There are several patent classification schemes that are in use by different patent authorities but International Patent Classification (IPC) is by far the most popular and more universally applied. For example, UK Patent Office withheld using its own classification system (UKC) in favour of IPC since July 2007. More than 70 patent granting authorities are believed to be using the IPC codes.

The World Intellectual Property Organization (WIPO) maintains the International Patent Classification (IPC). The IPC is represented as a collection of alphanumeric codes. Each code refers to different types of technical information. Each patent document published is likely to have at least one IPC code applied to it. The European Patent Office (EPO) and other patent offices world over also use it as well as their own classification codes to classify their own patent documents, e.g., United States Patent and Trademark Office (USPTO) and the Japan Patent Office (JPO).

European Classification System (ECLA)

ECLA is another significant classification scheme which is maintained by the European Patent Office (EPO). ECLA codes are applied to European patent documents as well as to documents from other patent offices that are being included in their global database (EPO worldwide referred as Esp@cenet). This classification is essentially based on the structure of International Patent Classification system and can be regarded as an extension of the same duly modified to suit its own requirements. ECLA is fairly detailed at the sub-groups level and quite precise having twice as many entries totaling to more than 140000. In most cases, IPC and ECLA classes are identical but ECLA sub-groups extend beyond the IPC sub-groups. Patent searching through ECLA codes in the European worldwide Esp@cenet which covers patent documents from as many as 70 different patent offices of the world has, thus, become very popular in the recent times. ECLA codes are also used on patent applications under ‘Patent Cooperation Treaty (PCT)’.

Cooperative Patent Classification (CPC)

It is a paradox that in spite of a number of very well evolved schemes of patent classification in vogue, one is never sure to have found all relevant patents while searching from various jurisdictions belonging to any precise technical field. Ideally there should be one, highly detailed patent classification that everyone uses on published patent documents. This would make life simpler and patent searching for prior art or for seeing technology development trends. In fact, the launch of Cooperative Patent Classification (CPC) project is the first major step in that direction.

Back in October of 2010, the USPTO and EPO announced the launch of a joint program designed to harmonize their patent classification systems. This program, is aimed at creating a single classification system based on the International Patent Classification scheme administered by WIPO and to be used by both offices. Once operational, this new system should greatly improve patent searches and examinations across the two major patent jurisdictions. This would also eliminate the use of patent classification concordance between the two jurisdictions. It is interesting to note that this new system has been touted to benefit the innovators by way of facilitating the access of technical information contained in patent documents and the main objective of the program is stated to be “Improving patent searching”.

It is stated that the migration to CPC will be developed based in large part on the existing European Classification System (ECLA) and would comply with the standards of IPC administered by WIPO. As per the timeline / milestones set by the program, CPC is projected to be launched in January 2013, i.e., in about nine months from now. The other intermediate milestones as proposed are freezing of both ECLA (1 July 2012) and the USPC (1 November 2010). This timeline suggests that both USPC and ECLA would soon be things of the past replaced by what is known as CPC.

Among the deliverables, the program aims to produce CPC definition for each class for a technical field. Suitable changes in the format and coding is also proposed. For example, alpha-numeric ECLA code will be transformed to purely numeric codes in CPC, as exemplified in the following case:

H01L21/027 H01L21/027 H01L21/027
H01L21/027B H01L21/02709
H01L21/027B2 H01L21/02718
H01L21/027B6 H01L21/027027
H01L21/027B6B H01L21/02736


There is no doubt that patent searching is going to be greatly simplified with the launch of CPC early next year. What is more, the new classification is expected to be adopted by major patent jurisdictions as soon as this is available since the program is being implemented under the aegis of IP5. As a next step, one can expect that most other patent jurisdictions, particularly those that have already embraced IPC would follow the suit to migrate to CPC and would find it perfectly feasible to do so. When this happens, global technology competitor analysis would become a matter of routine.


Cooperative Patent Classification

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