Can a patent undergo multiple reexaminations?

Yes, a patent can undergo multiple reexaminations. This is evident from the concept of “reexamination of a reexamination” discussed in MPEP § 2695. The section states:

“…a reexamination request filed on a patent for which a reexamination certificate has already issued, or a reexamination certificate issues on a prior reexamination, while the new reexamination is pending.”

This indicates that a patent can be subject to multiple rounds of reexamination, either sequentially or concurrently. Each reexamination may result in a new reexamination certificate, and subsequent reexaminations can be requested even after a certificate has been issued. This process allows for ongoing scrutiny of patent validity throughout its lifetime.

To learn more:

• multiple reexaminations
• patent validity
• reexamination certificate
• ongoing patent scrutiny