In The Dow Chemical Co. v. NOVA Chemicals Corp., Appeal Nos. 2014-1431, 2014-1462, the Federal Circuit reversed an award of supplemental damages due to the change in the law of indefiniteness, finding asserted claims indefinite because of the existence of multiple, potentially outcome-affecting methods for measuring a claim parameter.

Dow sued NOVA for infringing patents related to plastics.  A jury found the asserted claims infringed and not invalid, and the Federal Circuit initially affirmed, holding that the claims were not indefinite.  The district court then awarded supplemental damages for the period between the first judgment and the patents’ expiration.  NOVA appealed.  While the appeal was pending, the Supreme Court decided Nautilus Inc. v. Biosig Instruments, Inc., 134 S. Ct. 2120 (2014), in which the Supreme Court held that a claim is indefinite if it does not inform a person of skill in the art about its scope with reasonable certainty. 

The Federal Circuit reversed the award of supplemental damages, finding the asserted claims indefinite underNautilus.  The Federal Circuit held that neither issue preclusion nor law of the case bound it to the earlier conclusion of no invalidity.  The Federal Circuit reasoned that an exception to both doctrines applied because the prior appeal was decided under a different legal standard, and the law had since changed in a way that would alter the outcome of the case.  The Federal Circuit explained the tough new standard for claim definiteness under Nautilus as follows: “[where there are plural methods to determine a claim parameter, t]he question is whether the existence of multiple methods leading to different results without guidance in the patent or the prosecution history as to which method should be used renders the claims indefinite. Before Nautilus, a claim was not indefinite if someone skilled in the art could arrive at a method and practice that method.”

Reaching the merits of the indefiniteness issue, the Federal Circuit ruled that the limitation “slope of strain hardening coefficient” was indefinite because there were multiple methods that one could use to measure it, each yielding a different result.  Thus, the choice of method could impact whether a product infringed the claims.  Although the Federal Circuit previously concluded that a person of skill in the art could determine some way to measure the slope, the existence of multiple, potentially outcome-affecting methods rendered the claims indefinite under Nautilus.