How does ex parte reexamination affect intervening rights?

Ex parte reexamination can affect intervening rights in the following ways:

• If claims are amended or new claims are added during reexamination, intervening rights may apply to these changed or new claims.
• Intervening rights only apply to claims that are not substantially identical to the original claims.
• The effective date for intervening rights is the date of the reexamination certificate, not the original patent date.

According to MPEP 2293: “35 U.S.C. 307(b) provides that the intervening rights provisions of 35 U.S.C. 252 apply to ex parte reexamination proceedings.”

This means that parties who relied on the original patent claims may be protected from infringement liability for actions taken before the reexamination certificate is issued, if the claims are substantially changed during reexamination.

To learn more:

• ex parte reexamination
• intervening rights
• patent claims
• reexamination certificate