A claimed value that can be measured in several ways may be held to be indefinite rather than simply broad when the different measurements produce different results. Here, for example, a slope of strain hardening coefficient claimed within a certain range was found to be indefinite because of the existence of multiple methods for measuring the coefficient that would lead to different results, without guidance in the patent or the prosecution history as to which method should be used. “[A] claim term is indefinite if it leave[s] the skilled artisan to consult the unpredictable vagaries of any one person’s opinion.” It may therefore be best to ensure that the specification makes clear which measurement technique is appropriate for a claimed value, especially when different measurement techniques may produce drastically different results.
Background / Facts: The patents being asserted here are directed to ethylene polymer compositions (a type of plastic) with improved modulus, yield strength, impact strength, and tear strength. The claims recite “a slope of strain hardening coefficient greater than or equal to 1.3.” Strain hardening is a property wherein a material becomes harder as it is stretched. It is not disputed that there are at least four methods to determine the recited slope, and that each of the methods may produce different results, i.e., a different slope. Neither the patent claims nor the specification nor the prosecution history, however, discusses the four methods or provides any guidance as to which method should be used or even whether the possible universe of methods is limited to these four methods.
Issue(s): Whether, under the Supreme Court’s precedent in Nautilus, 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.
Holding(s): Yes. “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. … The claims here are even more clearly indefinite than those in Teva,” where “each [of three relevant measures for molecular weight] was calculated in a different manner and each typically had a different value.”