Understanding File Wrapper Estoppel: Key Concepts and Legal Insights

Definition & Meaning

File wrapper estoppel, also known as prosecution history estoppel, is a legal principle in U.S. patent law. It indicates that when a patent applicant makes amendments to their application to overcome prior art, they cannot later claim that a competitor's product infringes on the original, unamended claims of their patent. This principle helps ensure that the scope of patent protection is clear and prevents inventors from broadening their claims after narrowing them during the application process.

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Real-world examples

Here are a couple of examples of abatement:

(Hypothetical example) An inventor files a patent application for a new type of engine. To avoid rejection due to prior art, they amend their claims to specify a particular fuel type. Later, they attempt to sue a competitor for using a similar engine that uses a different fuel type. Under file wrapper estoppel, the inventor may be barred from claiming infringement because they narrowed their claims during the application process.

What to do if this term applies to you

If you are involved in a patent dispute or are considering filing a patent application, it's important to understand how file wrapper estoppel may affect your case. Consider consulting with a patent attorney for tailored advice. Additionally, you can explore US Legal Forms for templates that can assist you in preparing your patent application and related documents.

Quick facts

Attribute Details
Legal Area Patent Law
Key Case Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.
Implications Limits claims based on amendments made during prosecution

Key takeaways

Frequently asked questions

It is a legal principle that prevents a patent holder from claiming infringement based on claims that were narrowed during the patent application process.