What is a divisional patent application?
A divisional patent application is an application claiming priority from some previously filed patent application
(called a “parent application”) in which more than one invention was disclosed. The divisional application has
claims directed to a different invention than that claimed in the parent application. The most common way that this
happens is that the Patent Office rules that your application contains more than one invention, communicating this
in what is called a “restriction requirement”. The applicant then elects to pursue one of the inventions in that
application (the “parent application”), and optionally submits a “divisional application” containing the claims
regarding another of the inventions. The divisional application is entitled to the filing date of the parent application
as its priority date. It is not uncommon to receive a restriction requirement identifying several inventions, leading to
several divisional applications and several issued patents.
Under GATT, if the application was filed prior to June 8, 1995, it is disadvantageous to file a divisional application
since the divisional application may end up with a shorter patent term. One option, if the application was filed prior
to June 8, 1992, is to use a rule under GATT in which the applicant pays a fee (equal to the cost of a new filing
fee) to have the extra invention considered in the same application rather than in a divisional application.