China: Interpretation Of Unity Provisions In PCT

Last Updated: 22 October 2015
Article by George Y. Tang

The unity principle, also known as the principle of "one application for one invention", means that one patent application shall be limited to one invention. The unity principle is a fundamental principle for patent applications, and in addition to state or regional patent laws in the world, PCT (Patent Cooperation Treaty) defines this principle.

It becomes a universal principle for a number of reasons. The first is economic consideration. The patent examination organization requires the applicants to pay certain fees to maintain the normal operation of the organization and enable it to complete the search and examination of patent applications. Typically, the fee paid by an applicant is based on the number of patent applications. If the number of inventions included in a patent application is not limited, an applicant may only pay the fee for a patent application, but request to examine a number of inventions, leading to heavy economic burden of the patent examination organization. The second is the management consideration of the patent examination organization. That a patent application relates to one invention only facilitates the classified management of the patent application (e.g. use of the international patent classification number), and further facilitates the assignment to the examiner of the related technical field for search and examination. Moreover, such classified management also facilitates the public use of patent information, including the consultation of the prior art in the related technical field. However, from the foregoing reasons, the unity principle is only a formal requirement and does not involve a substantive condition of granting a patent right. Therefore, the lack of unity is usually not deemed to be a reason for invalid patent right.

The unity provisions in PCT are described in detail as follows. According to Article 13.1 of the Implementing Rules of the PCT, an international application shall relate to one invention or a group of inventions so linked as to form a single general inventive concept only. According to this article, there are two circumstances under which the unity of invention is required: one invention is involved only; a group of inventions so linked as to form a single general inventive concept is involved only. The former circumstance is a pure embodiment of the unity principle. The latter circumstance can be seen as an extension of the former circumstance, that is, when a group of inventions is linked together as to form a single general inventive concept, the group of inventions can be regarded as "one invention" so that it can comply with the unity principle. Obviously, the latter circumstance is a difficulty in the determination of unity.

Before determining unity, we need to clarify a fundamental question: What is the object of determination of unity? That is, for one patent application, what is the basis of the patent examination organization for determination of unity? Although the unity principle is generally described as "one patent application shall be limited to one invention", it actually means that "one patent application shall only claim one invention". Therefore, the determination of whether a patent application meets the requirement of unity is based on the contents of the claims rather than the description. In theory, in addition to technical contents corresponding to the claims, the description can describe all kinds of contents unrelated to claims such as multiple unrelated inventions. Such descriptions will not be subject to the unity principle, and examiners will at most indicate the preparation defects of the descriptions themselves (e.g. wording and sentence problems) or whether an invention is disclosed sufficiently. However, once an applicant tries to write other inventions recorded in the description into the claims (including replacement of the original claims), the application will be subject to the unity principle.

Back to the determination of unity itself, we need to explain what is "a single general inventive concept"? Only from the literal meaning, it is a relatively broad term and difficult to precisely define the scope. For example, do all technical solutions designed to improve the combustion efficiency of engines belong to a single general inventive concept? In this regard, Article 13.2 of the Implementing Rules of the PCT gives an explanation: Where a group of inventions is claimed in one international application, the requirement of unity of invention referred to in Article 13.1 thereof shall be deemed as met only when there is a technical relationship among those inventions involving one or more same or corresponding special technical features. The expression "special technical features" shall mean those technical features that define a contribution which each of the claimed inventions, considered as a whole, makes over the prior art.

According to the aforesaid provisions, for a group of inventions claimed in one claim, the technical relationship among them is not broad and arbitrary and is deemed to exist only when their technical solutions contain at least one same or corresponding special technical feature. In such case, they are determined to belong to "a single general inventive concept", and thus meet the requirement of unity. Therefore, by introducing the concept of "special technical feature", there is a specific and clear operational standard for determining whether several technical solutions belong to "a single general inventive concept".

The "special technical feature" is a concept designed to determine unity. It shall be understood as the technical feature defining contributions of the inventions to the prior art and giving novelty and creativity of the inventions compared with the prior art, and it shall be determined after each of the claimed inventions is considered as a whole. Thus, unity and inventiveness are linked together through the concept. Here, the main possible reason for emphasis on "each of the claimed invention is considered as a whole" is that: the inventiveness shall be determined based on the whole technical solution defined by the claims, that is, we shall evaluate whether the technical solution, rather than a technical feature, has inventiveness. However, for the determination of unity, we only need to find the technical relationship among different technical solutions and the technical relationship is just embodied on a single technical feature. Therefore, to consider the integral determination of inventiveness and the single determination of unity, the concept of "special technical feature" deliberately points out that when the technical solution of the invention as a whole has inventiveness, a single technical feature that plays a decisive role in term of inventiveness in the technical solution is the special technical feature embodying the technical relationship.

According to the understanding above, if a group of inventions does not involve a same or corresponding technical feature, they may not involve a same or corresponding special technical feature obviously and thus do not have unity. If the same or corresponding technical feature contained is common knowledge in the field, the technical feature may not play a decisive role in the inventiveness of relevant technical solution obviously, and therefore is not a specific technical feature and such inventions clearly do not have unity. In addition to these two distinct circumstances without unity, unity needs to be determined typically after comparison with the prior art and determination of inventiveness. Therefore, unity is often not determined by the receiving office or the international office, but by the international searching authority or the international preliminary examination authority or even by the designated state office.

In the international phase of a PCT application, if an international patent application fails to meet the requirement of unity, generally, the examiner shall indicate such failure and require the applicant to pay fees for the search or examination of additional invention. When an examiner can search the additional inventions by the negligible additional effort and especially when these inventions are very close in terms of ideas, the examiner may decide to search all inventions but should still point out the lack of unity in the application. However, the international preliminary examination authority generally does not perform international preliminary examination on the claims without the international search report. When the examiner points out the problem of unity and requires the applicant to pay a surcharge, the applicant can raise an objection at payment of the surcharge (an objection fee is required to be paid at the same time), and the objection should state that the application complies with the requirement of unity or that the surcharge is too high. In such case, the international searching authority or the national preliminary examination authority shall start the objection procedure and give a ruling on the applicant's objection.

It should be noted that when the international searching authority and/or international preliminary examination authority does not search all the claims, it will not affect validity of this international patent application, and a designated state (or selected state) can still consider all the claims. Of course, the designated state (or selected state) can also require the applicant to pay related fees in accordance with its national laws, otherwise the parts of the international patent application that are not searched and/or examined are deemed to be withdrawn.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on

Click to Login as an existing user or Register so you can print this article.

Similar Articles
Relevancy Powered by MondaqAI
Some comments from our readers…
“The articles are extremely timely and highly applicable”
“I often find critical information not available elsewhere”
“As in-house counsel, Mondaq’s service is of great value”

Related Topics
Similar Articles
Relevancy Powered by MondaqAI
Related Articles
Related Video
Up-coming Events Search
Font Size:
Mondaq on Twitter
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
Email Address
Company Name
Confirm Password
Mondaq Topics -- Select your Interests
 Law Performance
 Law Practice
 Media & IT
 Real Estate
 Wealth Mgt
Asia Pacific
European Union
Latin America
Middle East
United States
Worldwide Updates
Registration (you must scroll down to set your data preferences)

Mondaq Ltd requires you to register and provide information that personally identifies you, including your content preferences, for three primary purposes (full details of Mondaq’s use of your personal data can be found in our Privacy and Cookies Notice):

  • To allow you to personalize the Mondaq websites you are visiting to show content ("Content") relevant to your interests.
  • To enable features such as password reminder, news alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our content providers ("Contributors") who contribute Content for free for your use.

Mondaq hopes that our registered users will support us in maintaining our free to view business model by consenting to our use of your personal data as described below.

Mondaq has a "free to view" business model. Our services are paid for by Contributors in exchange for Mondaq providing them with access to information about who accesses their content. Once personal data is transferred to our Contributors they become a data controller of this personal data. They use it to measure the response that their articles are receiving, as a form of market research. They may also use it to provide Mondaq users with information about their products and services.

Details of each Contributor to which your personal data will be transferred is clearly stated within the Content that you access. For full details of how this Contributor will use your personal data, you should review the Contributor’s own Privacy Notice.

Please indicate your preference below:

Yes, I am happy to support Mondaq in maintaining its free to view business model by agreeing to allow Mondaq to share my personal data with Contributors whose Content I access
No, I do not want Mondaq to share my personal data with Contributors

Also please let us know whether you are happy to receive communications promoting products and services offered by Mondaq:

Yes, I am happy to received promotional communications from Mondaq
No, please do not send me promotional communications from Mondaq
Terms & Conditions (the Website) is owned and managed by Mondaq Ltd (Mondaq). Mondaq grants you a non-exclusive, revocable licence to access the Website and associated services, such as the Mondaq News Alerts (Services), subject to and in consideration of your compliance with the following terms and conditions of use (Terms). Your use of the Website and/or Services constitutes your agreement to the Terms. Mondaq may terminate your use of the Website and Services if you are in breach of these Terms or if Mondaq decides to terminate the licence granted hereunder for any reason whatsoever.

Use of

To Use you must be: eighteen (18) years old or over; legally capable of entering into binding contracts; and not in any way prohibited by the applicable law to enter into these Terms in the jurisdiction which you are currently located.

You may use the Website as an unregistered user, however, you are required to register as a user if you wish to read the full text of the Content or to receive the Services.

You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these Terms or with the prior written consent of Mondaq. You may not use electronic or other means to extract details or information from the Content. Nor shall you extract information about users or Contributors in order to offer them any services or products.

In your use of the Website and/or Services you shall: comply with all applicable laws, regulations, directives and legislations which apply to your Use of the Website and/or Services in whatever country you are physically located including without limitation any and all consumer law, export control laws and regulations; provide to us true, correct and accurate information and promptly inform us in the event that any information that you have provided to us changes or becomes inaccurate; notify Mondaq immediately of any circumstances where you have reason to believe that any Intellectual Property Rights or any other rights of any third party may have been infringed; co-operate with reasonable security or other checks or requests for information made by Mondaq from time to time; and at all times be fully liable for the breach of any of these Terms by a third party using your login details to access the Website and/or Services

however, you shall not: do anything likely to impair, interfere with or damage or cause harm or distress to any persons, or the network; do anything that will infringe any Intellectual Property Rights or other rights of Mondaq or any third party; or use the Website, Services and/or Content otherwise than in accordance with these Terms; use any trade marks or service marks of Mondaq or the Contributors, or do anything which may be seen to take unfair advantage of the reputation and goodwill of Mondaq or the Contributors, or the Website, Services and/or Content.

Mondaq reserves the right, in its sole discretion, to take any action that it deems necessary and appropriate in the event it considers that there is a breach or threatened breach of the Terms.

Mondaq’s Rights and Obligations

Unless otherwise expressly set out to the contrary, nothing in these Terms shall serve to transfer from Mondaq to you, any Intellectual Property Rights owned by and/or licensed to Mondaq and all rights, title and interest in and to such Intellectual Property Rights will remain exclusively with Mondaq and/or its licensors.

Mondaq shall use its reasonable endeavours to make the Website and Services available to you at all times, but we cannot guarantee an uninterrupted and fault free service.

Mondaq reserves the right to make changes to the services and/or the Website or part thereof, from time to time, and we may add, remove, modify and/or vary any elements of features and functionalities of the Website or the services.

Mondaq also reserves the right from time to time to monitor your Use of the Website and/or services.


The Content is general information only. It is not intended to constitute legal advice or seek to be the complete and comprehensive statement of the law, nor is it intended to address your specific requirements or provide advice on which reliance should be placed. Mondaq and/or its Contributors and other suppliers make no representations about the suitability of the information contained in the Content for any purpose. All Content provided "as is" without warranty of any kind. Mondaq and/or its Contributors and other suppliers hereby exclude and disclaim all representations, warranties or guarantees with regard to the Content, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. To the maximum extent permitted by law, Mondaq expressly excludes all representations, warranties, obligations, and liabilities arising out of or in connection with all Content. In no event shall Mondaq and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use of the Content or performance of Mondaq’s Services.


Mondaq may alter or amend these Terms by amending them on the Website. By continuing to Use the Services and/or the Website after such amendment, you will be deemed to have accepted any amendment to these Terms.

These Terms shall be governed by and construed in accordance with the laws of England and Wales and you irrevocably submit to the exclusive jurisdiction of the courts of England and Wales to settle any dispute which may arise out of or in connection with these Terms. If you live outside the United Kingdom, English law shall apply only to the extent that English law shall not deprive you of any legal protection accorded in accordance with the law of the place where you are habitually resident ("Local Law"). In the event English law deprives you of any legal protection which is accorded to you under Local Law, then these terms shall be governed by Local Law and any dispute or claim arising out of or in connection with these Terms shall be subject to the non-exclusive jurisdiction of the courts where you are habitually resident.

You may print and keep a copy of these Terms, which form the entire agreement between you and Mondaq and supersede any other communications or advertising in respect of the Service and/or the Website.

No delay in exercising or non-exercise by you and/or Mondaq of any of its rights under or in connection with these Terms shall operate as a waiver or release of each of your or Mondaq’s right. Rather, any such waiver or release must be specifically granted in writing signed by the party granting it.

If any part of these Terms is held unenforceable, that part shall be enforced to the maximum extent permissible so as to give effect to the intent of the parties, and the Terms shall continue in full force and effect.

Mondaq shall not incur any liability to you on account of any loss or damage resulting from any delay or failure to perform all or any part of these Terms if such delay or failure is caused, in whole or in part, by events, occurrences, or causes beyond the control of Mondaq. Such events, occurrences or causes will include, without limitation, acts of God, strikes, lockouts, server and network failure, riots, acts of war, earthquakes, fire and explosions.

By clicking Register you state you have read and agree to our Terms and Conditions