Examining File History information contained in the file history may be very important to analyze a particular patent. The information in the file history helps to fully understand the scope of claims of the patent (prosecution history estoppel), and further can be used to demonstrate the nature of the invention, important dates of the examination process, amendments made, and more.
The file history becomes particularly relevant in case of patent infringement litigation. In such a case, the defending party may analyze the file history of the patent to ascertain the scope of the claims of the patent, and try to invalidate or, at least, frame arguments to narrow the scope of the claims, so that the infringement allegations may be thwarted.
The file history may be analyzed for:
- History Documents: File history contains many documents ranging from original drawings to amendments made. These documents can help to understand the scope of the claims as considered by the applicant when patenting their invention.
- Prior-art References: Patent examiner generally performs an exhaustive search during prosecution to identify relevant prior-art documents, which are cited against the patent even if the same is not thoroughly analyzed. Sometimes, because of lack of sufficient time and resources, the examiner may oversee a particular reference which could turn out to be a crushing prior-art for the patent. Such information may be pulled from file histories.
- Invention Changes: The patent file history may be studied to learn about all the changes made in the claims, description, drawings, etc. during prosecution. It could help determine what aspects of the patent were accepted and what were rejected. This could provide clues which may be used in litigation.
- Document Dates: A timeline of a patent could be drawn by using information, such as dates on non-final rejection letters or patent grants, etc., available in the file history. This may be helpful in framing arguments (in consideration of the prior-art) against the patent during legal proceedings in the Court.
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