By Rich Stim
In this article we discuss interferences, divisional applications, reissue applications, substitute applications, and double patenting. All of these topics relate to problems that may arise during patent prosecution.
An interference is a costly, complex PTO proceeding to determine who will get a patent when two or more applicants are claiming the same invention. In other words, it is a method of sorting out inventorship priority. Approximately 2% of applications become involved in interferences. The PTO institutes an interference when two patent applications are filed claiming the same invention. Occasionally, an interference may involve a patent that has been in force for less than one year. During an interference, the PTO determines which inventor first reduced the invention to practice. (Note: In the event the U.S. Passes patent reform -- as explained in this article – interference hearings may eventually disappear to be replaced by “derivation hearings.”)
If a patent application contains more than one invention, the PTO will require that it be “restricted” to just one of the inventions. That’s because the application fee entitles an applicant to have only one invention examined. Generally speaking, it’s very difficult to successfully argue against (or “traverse”) this type of PTO-imposed restriction. The only solution to protect several inventions claimed in the original application is to file a divisional application. The official definition of a divisional application is “a later application for a distinct or independent invention, carved out of a pending application and disclosing and claiming only subject matter disclosed in the earlier or parent application” (MPEP 201.06). A divisional application is entitled to the filing date of the parent case for purposes of overcoming prior art. The divisional application must be filed while the parent application is pending.
A reissue application is an attempt to correct information in an issued patent. It is usually filed when a patent owner believes:
- the claims are not broad enough
- the claims are too broad (the applicant discovered a new reference), or
- there are significant errors in the specification.
In these cases, an attempt is made to correct the patent by filing an application to have the original patent reissued at any time during its term. The reissue patent will take the place of the original patent and expire at the same time as the original patent would have expired. If the purpose is to broaden the claims of the patent through a reissue application, the applicant must do so within two years from the date the original patent issued. There is a risk in filing a reissue application because all of the claims of the original patent will be examined and can be rejected.
If a patent application is abandoned, a substitute application can be filed that is essentially a duplicate of the abandoned application (see MPEP 201.09). The disadvantage of a substitute application is that the filing date of the previously abandoned patent application is not retained. Any prior art occurring after the filing date of the earlier case can be used against the substitute case. If the substitute application issues into a patent, the patent will expire 20 years from the filing date of the substitute.
If a patent is issued and the patent owner files a second application containing the same invention (“double patenting”), the second application will be rejected, or if the second application resulted in a patent, that patent will be invalidated. What does it mean when two applications contain the same invention? It means either that the two inventions are literally the same or that the second invention is an obvious modification of the first invention.
EXAMPLE: An inventor applied for a patent on polymer dispersants used in motor oil to keep engines clean. A patent issued in 1989. A continuation application was filed incorporating similar, but slightly broader claims. The Court of Appeals for the Federal Circuit (CAFC) ruled that the continuation application was invalid for double patenting because it was an obvious modification of the first application.
In the example above, the applicant could avoid double patenting by agreeing that both patents would terminate on the date when the first patent ended (known as a “terminal disclaimer”).
The following articles address other issues that commonly arise in patent prosecution:
- Responding to a First Office Action
- Responding to a Final Office Action
Portions of this article are derived from Nolo's Patents for Beginners.