During patent file history the patent examination process, called “prosecution”, the patent examiner will examine the patent application to determine if the requirements for obtaining a patent are met. The patent “file history”, also sometimes known as “file wrapper” (particularly for US patents) is a record which contains all of the documents pertaining to a particular patent application, including those generated during prosecution. The file history, includes, among other, all of the documents relating to the patent such as diagrams and drawings; communications between the patent Office and the applicant (or its attorney/agent); statements made by the applicant; and records of official actions by the patent Office. The file history may also include records of interviews of the applicant conducted by the Patent Office. Most of the patent offices; including USPTO, EPO and even Indian Patent Office provide the option for users to search for a file history of a patent or application. That is, information in the file wrapper is in the public domain and can be examined by anyone who requests it.
The 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, discussed below), and further can be used to demonstrate the nature of the invention, important dates of the examination process, amendments made, and more.
Probably the most important use of the file history is in the establishment of prosecution history estoppel, for example in the event of a lawsuit or contentious litigation over patent invalidation/infringement hearings. For such proceedings, it is important to determine the scope of the claims of the patent; and for determining the scope it is important to look at the claims, the description of the invention, and at the statements made by the applicant in the file history. For example, statements made during prosecution by the applicant can help define or narrow a term in the claims. Further, these statements may be used to interpret an ambiguous or unclear word or phrase in the claims. Furthermore, the applicant’s statements in the file history as to the content and scope of the prior art can be very helpful in interpreting the scope of the claims alleged to be infringed. So it may be understood that analyzing the content of the file history is always important to fully determine the content of a patent.
