What Is a Terminal Disclaimer?

Introduction

A terminal disclaimer is part of patent continuation practice. It is a document filed with the USPTO that ties the term of a patent arising from a continuation filing to another patent. This article explains the purpose of terminal disclaimers, when they are used, and what they mean. Spoiler: Now that US patent terms are 20 years from initial filing rather than 17 years from patent issuance, they are not nearly as big a deal as they once were.

Purpose of Terminal Disclaimer

The main purpose of a terminal disclaimer is to address double patenting issues. Double patenting is when an applicant seeks multiple patents for the same invention. In the past, when patent terms were 17 years from the date of issuance, filing multiple continuations was a loophole that extended monopoly rights beyond what patent law intended. Terminal disclaimers are a somewhat vestigial leftover from that era (although they do limit patent terms in some cases).

When Is a Terminal Disclaimer Used?

When two patents or patent applications contain claims that are not patentably distinct from each other, the examiner often issues a double patenting rejection. Double patenting is a judicially created rule, so you won’t find it in the U.S. Code, but that’s a technicality. Filing a terminal disclaimer is the only guaranteed way to overcome a double patenting rejection

Implications of Terminal Disclaimer

By filing a terminal disclaimer, patent holders limit the term of a later patent to end when the term of an earlier patent ends.

Conclusion

Terminal disclaimers are somewhat common in continuation patent prosecution. Understanding what they are and how they impact your IP portfolio is critical.