
Today the Federal Circuit held that a party joining an existing IPR is not subject to estoppel on any grounds other than those that were actually raised. See the opinion below.
Before this, a plaintiff could argue that a defendant who joined an in-progress IPR was estopped on any anticipation or obviousness arguments that "reasonably could have [been] raised" in the IPR.
The Court here held, in short, that because a defendant joining an existing IPR is not allowed to add new grounds at all, it cannot be estopped except on those grounds actually raised.
It relied on the Facebook decision we talked about …