ArcelorMittal France v. AK Steel Corp., ___F.3d ___ (Fed. Cir. May 12, 2015) (Dyk, Wallach, HUGHES) (D. Del.: Robinson) (3 of 5 stars)

Federal Circuit affirms-in-part and reverses-in-part judgment of invalidity due to impermissible broadening during reissue.

ArcelorMittal applied for reissue of its patent while a prior appeal stemming from this litigation was ongoing.  Original 1 claim included a limitation requiring “a very high mechanical resistance,” and the reissue added dependent claim 23, which required mechanical resistance “in excess of 1000 MPa.”  The Federal Circuit’s prior opinion, however, had construed the mechanical resistance limitation in the original clam as limited to “greater than 1500 MPa.”

The district court properly held that claims 1 through 23 were impermissibly broadened.  The Federal Circuit’s prior interpretation of claim 1 controlled interpretation of original claim 1; post-reissue, claim 1 had broader scope due to the addition of claim 23.  The addition of claim 23 is not “new evidence” that might permit revisiting the interpretation of original claim 1 under either law of the case or the mandate rule.  A reissue claim cannot be used to redefine the scope of an original claim.  And while reissue prosecution history is sometimes relevant to determining the scope of original claims, such history is not relevant to determining whether broadening of an original claim has occurred.

The district court erred, however, in holding that because some claims of the reissue patent had been impermissibly broadened, all reissue claims were invalid.  Invalidity due to impermissible broadening is evaluated claim-by-claim.  There was no dispute that claims 24 and 25 (which were added during reissue) had the same scope as original claim 1, and so no broadening occurred.