According to Rule 42 (1) of the Implementing Regulations of the Patent Law of China, for a patent application containing two or more inventions, utility models or designs, the applicant may, before the expiration of the two-month period from the date of receipt of the notification to grant the patent right, submit a divisional application; however, for a patent application that has been rejected, withdrawn or is deemed to have been withdrawn, no divisional application may be filed.

    From the provisions stated above, it seems that the reasons for filing a divisional application seem very simple. However, in practice, there is a great diversity of purposes for filing a divisional application.  Generally speaking, it may be classified into two types: passively filed-divisional application and actively filed-divisional application.

    Passively Filed-Divisional Application

    When a rejection of lack of unity is raised in an Office Action, the applicant may restrict the two or more inventions that do not have unity therebetween to one invention, and submit one or more divisional application(s) for any invention removed. This is the most commonly filed divisional application.

    Actively Filed-Divisional Application

    Many countries allow the applicant to have opportunities for filing voluntary amendments based on the above-mentioned divisional application system and other similar systems. In this case, the patent attorney may seek for a more reasonable and adequate patent protection for the applicant by filing one or more actively filed-divisional application(s). Specifically, reasons for filing an actively filed-divisional application can be roughly divided into the following situations.

    1. In the examination process of an application, it often occurs that there is a large discrepancy between the opinions of the applicant and the examiner on the evaluation of the patentability of technical solutions of certain claims, causing the examination period of the application to be longer and its prospects for being granted bleak.

    In this situation, in order to break the deadlock in the examination process, the applicant may first amend the initial claims according to the requirements of the examiner and then file a divisional application based on the initial set of claims to seek a broader scope of protection.

    2. For one reason or another, the documents of an initial application may have some defects, for example the technical solution that the applicant really wants to protect or actually has the largest market value is just deviated from the technical solution disclosed in the description rather than those claimed in the claims concerning examination.

    In this case, as long as the divisional application does not go beyond the scope of the disclosure contained in the initial application, the applicant may seek protection for the technical solution that the applicant really wants to protect or the technical solution that has the largest market value by filing a divisional application.

    3. In the case that an application has been rejected or is under the reexamination procedure, and its prospects for being granted are not optimistic, if such an unfavorable situation is caused by, for example, some flaws in the description and/or claims of the application and there are some technical solutions with protective value, the applicant may file a divisional application at this point to protect such technical solutions. In this way, even if the initial application is finally rejected, the applicant still has the opportunity to protect the technical solutions with protective value by filing a divisional application.

    4. As known to all, once an application is published, the contents described in the application will be known by the public. Therefore, from the perspective of the applicant, of course, it is hoped that all the technical solutions with protective value in the application can be protected.

    An effective way is to amend the initial claims to cover as many technical solutions with protective value disclosed in the description as possible.  However, according to Rule 51(3) of the Implementing Regulations of the Patent Law of China, where the applicant amends an application after receiving the notification of the substance examination, he or it shall make the amendment with respect to the defects as pointed out in the notification.  Therefore, for the application that is under examination, amendments to the claims may be restricted which are deemed as not overcoming the defects indicated. Under such a situation, by filing a divisional application, the technical solutions with protective value that are only described in the description but not claimed in the claims can be drafted as new claims and protected.

    5. In normal circumstances, the applicant may have sufficient time for seeking patent application strategy and drafting the relevant documents.  However, if the applicant does not have time to carry out the above-mentioned procedures step by step in an emergency, by placing all related technical solutions in one application and simply drafting multiple sets of claims that obviously lack of unity, the applicant can make full use of the divisional application system to share an earlier filing date for all the technical solutions. After doing so, the applicant can continue to improve the patent application strategy and then implement the strategy just at the right time by filing one or more divisional application(s)

    6. Similar to Item 5, the applicant may at first describe as many technical solutions as possible in one application and draft multiple sets of claims that obviously lack unity, and then the applicant may try to keep this parent application in a "pending" state for as long as possible. In this way, the applicant will have enough time to study the information especially concerning competitors' products. If one or more divisional application(s) that cover(s) the competitors' products can be filed, which will have great commercial value, it will be a big strike to the competitors.

    The author summarizes the above-mentioned cases and reasons for filing divisional applications, and hopes that such tips may be of help to the applicant.

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.