Prosecution history estoppel

The term "prosecution history estoppel" is a legal principle that applies to patent law in the United States. It is also known as "file wrapper estoppel" or "estoppel by prosecution history." Prosecution history estoppel limits the scope of a patent's claims during patent litigation and affects the rights of a patent holder.

Here's an explanation of prosecution history estoppel:

1. Patent Application Process: When an inventor seeks to obtain a patent for an invention, they submit a patent application to the United States Patent and Trademark Office (USPTO). During the examination process, the patent examiner reviews the application and may issue rejections or objections based on prior art or other reasons.

2. Amendments and Arguments: To overcome rejections or objections, the patent applicant may amend the claims of the patent application or make arguments to convince the examiner that the invention is patentable over the prior art. These amendments and arguments become part of the "prosecution history" or "file wrapper" of the patent application.

3. Prosecution History Estoppel: Prosecution history estoppel arises from the principle of "surrender" during patent prosecution. When a patent applicant makes amendments to the claims or makes certain arguments to secure the issuance of the patent, they may be surrendering or giving up claim scope. As a result, they are "estopped" from later asserting a broader claim scope during litigation that encompasses subject matter surrendered during prosecution.

4. Scope of Patent Claims: During patent litigation, if the accused infringer believes that the patent holder is attempting to assert a claim scope that goes beyond what was allowed by the patent examiner during prosecution, the accused infringer may raise the defense of prosecution history estoppel. The accused infringer can argue that the patent holder is estopped from asserting the broader claim scope because of the amendments and arguments made during prosecution.

5. Application and Impact: Prosecution history estoppel is an important principle in patent litigation because it narrows the interpretation and enforcement of patent claims, preventing patent holders from obtaining broader protection than they were initially granted by the patent office.

It's important to note that prosecution history estoppel is specific to the U.S. patent system and may not apply in the same way in other countries with different patent laws and practices. Additionally, the application of prosecution history estoppel can be complex and may require legal expertise and analysis in the context of a particular patent dispute.