A Defined Numerical Parameter Can Still Be Indefinite, If It’s Not Clear How to Measure It

In The Dow Chemical Co. v. Nova Chemicals Corporation (Canada), [2014-1431, 2014-1462] (August 28, 2015) the Federal Circuit applied the change of law exception to reject Dow’s bid for supplemental damages for infringements occurring after the original judgment — the change of law being the change of the standard of indefiniteness resulting from the Supreme Court decision in Nautilus, Inc. v. Biosig Instruments, Inc., 134 S. Ct. 2120 (2014).

The Federal Circuit found that its original decision would have been different under the new Nautilus standard.  The claims at issue require “a slope of strain hardening coefficient greater than or equal to 1.3.”  The patent explained that the slope of strain hardening
coefficient was a new Dow construct not previously known in the prior art, and is calculated by a given formula from the slope of strain hardening curve.  However, it turns out that the strain hardening curve is in fact curve, meaning it does not have a single slope.  .Nova complained that the patent fails to teach where and how the slope of strain hardening should be measured.  The Federal Circuit found that there were four ways to measure the slope, and that each of these four methods may produce different results, and because the methods do not always produce the same results, the method chosen
for calculating the slope of strain hardening could affect whether or not a given product infringes the claims.

Under Nautilus a patent is invalid for indefiniteness if its claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty,those skilled in the art about the scope of the invention.  The Federal Circuit held that “the required guidance is not provided by the claims, specification, and prosecution history.”  The Federal Circuit said that a claim term is indefinite if it “leave[s] the skilled artisan to consult the ‘unpredictable vagaries of any one person’s opinion.’” The Federal Circuit concluded that the claims here are invalid as indefinite, and the award of supplemental damages must be reversed.

While measured parameters with numerical values at first appear to be definite, patent drafters must be clear about how those parameters are measured — at least where the value can vary depending upon the method used.