What is a Divisional Application?
There is a whole world of 
patent applications beyond the original nonprovisional patent application. There are provisional, plant, design, reissue, divisional, continuation, continued prosecution, and continuation-in-part applications. These last four applications are known as continuing applications, because they continue from an original (nonprovisional) application in some way. Over the next few blog posts, I will explore each type of application.
Today, I’ll begin with a divisional application. A divisional application is an application that picks up subject matter that was divided out of an earlier application and then presents that subject matter for examination. They arise most frequently because a restriction requirement was made in the earlier application.
A restriction requirement is a requirement made by the Examiner when a patent application contains more than one invention or species of inventions; they are made because of the preclusion against a patent covering more than one invention – “one patent, one invention.” Restriction requirements are proper where an application includes claims to patentably distinct inventions, and they are often raised when an application contains claims to both a device and a process or method of using the device. Responding to the restriction requirement necessitates electing one of the inventions. An election selects a group of claims drawn to that invention for continued prosecution in the application. The remaining claims are carved from the application with leave to later file a divisional application or applications directed to those claims. Thus, a restriction requirement does not force the inventor to eliminate the other inventions, but instead, one invention is elected and the others are placed in a holding pattern until a divisional application is filed.
A divisional application can be filed on one of those “holding pattern” inventions, but it must be co-pending with the original application (or another application continuing from the original). To be co-pending, the later-filed application must be filed before either the abandonment of the earlier-filed application or the issuance of the earlier-filed application as a patent. Additionally, the divisional application must properly make a claim of priority to the earlier-filed application, and it cannot contain any matter that was not disclosed in the original application.
Once filed, the divisional application is prosecuted like any other patent application. The Examiner will perform a search on the claimed invention, objections and rejections will be issued, responses are made, and the application will hopefully be allowed. While a divisional application may seem like a headache because it involves an additional filing (and filing fees), it can be seen as an opportunity to receive more attentive examination, and perhaps better additional claims on the invention. Further, you may have learned something about the Examiner’s view of the greater inventive concept during prosecution of the original application which you can then apply to the divisional application to enhance the possibilities of an allowance.