What is the estoppel effect of litigation on inter partes reexamination under 35 U.S.C. 317(b)?

The estoppel effect under 35 U.S.C. 317(b) can prevent the maintenance of an inter partes reexamination under certain conditions:

• It applies when there’s a final court decision upholding patent validity.
• The requester must have been a party to the litigation.
• It only affects claims that were at issue in the litigation.
• It prevents reexamination based on issues that were raised or could have been raised in the litigation.

The MPEP states: Once a final decision has been entered against a party in a civil action arising in whole or in part under section 1338 of title 28, that the party has not sustained its burden of proving the invalidity of any patent claim in suit…, then neither that party nor its privies may thereafter request an inter partes reexamination of any such patent claim on the basis of issues which that party or its privies raised or could have raised in such civil action…

To learn more:

• inter partes reexamination
• estoppel
• litigation
• 35 U.S.C. 317(b)