A continuation in part application is a special type of patent application. Patent practice is complicated and subject to many considerations about past disclosures and uses of the subject matter as well as future handling of the application. This explanation is a brief description of what a continuation in part application generally is in comparison to other patent applications, and does not constitute legal advice. Please seek the guidance of a registered patent attorney if you are considering filing one of these or any patent application.
A continuation in part application follows on from a previously-filed case and creates a chain of cases from a senior, or parent, patent application with a child patent application. The child application possesses a link in subject matter with the parent application; some aspect of the invention or embodiments of the invention are common to both applications. A continuation in part application can be useful when you’ve made improvements to an existing invention that are so closely related that it would be desirable to place the new material in an application together with the old material, but the improvement are different enough that they were not realized and disclosed at the time of the parent application filing.
A continuation in part application carries old subject matter over from a parent patent application and then adds new subject matter that was not contained within the parent. Because the new matter was not contained in the parent application, that new matter does not get the benefit of the parent’s filing date, and so the claims of the new case can have different filing dates from that of the parent application. If claims in the child case are supported by the disclosure made in the parent application, then they will be given the filing date of the parent application; if there are claims which are supported only by the new subject matter, they will receive the new application’s actual date of filing.
The life of a patent was once measured from the grant date of the patent. When that was the case, by filing a continuation in part application, you could potentially increase the protected lifespan of the inventive subject matter. However, the law was changed so that patent protection now runs for twenty years from the effective filing date, which can be that of the parent application or even earlier. Child applications adopt the filing date of the earlier-filed application, and thus generally lose a few of those twenty years during prosecution of the prior case.
Continuation in part applications include include two types of claims: those that include subject matter disclosed completely in the prior application, and those that include subject matter supported by the new disclosure. The former claims receive the benefit of the earlier application’s filing date, while the latter claims get their own, new filing date. This split in filing dates can create issues that may direct an inventor to file an original application instead.
Filing a continuation in part application can be a very wise move if the claims are supported by the old disclosure. It can help you avoid intervening prior art by giving your new application an earlier filing date. However, if the application is filed and the claims aren’t supported by the old disclosure but only by the new disclosure, it makes no sense; the earlier application’s filing date is not available, but the life of the newly-filed application may still be shortened. In this case, these applications should probably be filed as original applications so as to begin with a fresh filing date. So, if there is new disclosure on which the claims are based, it can make more sense to file the claims in an original application rather than a continuation in part application.