The Federal Circuit has upheld a rule from the U.S. Patent and Trademark Office (USPTO) that allows the Patent Trial and Appeal Board (PTAB) to invalidate patent claims in subsequent office proceedings. However, in a specific case involving Apple and Motorola, the court determined that this rule does not apply to issued claims. This ruling clarifies the scope and timing of collateral estoppel for claims under inter partes review (IPR). Additionally, the court provided guidance on the scope of the estoppel provision and the concept of 'patentably distinct' claims.