Avoiding Indefiniteness Traps – Specifying Measurement Standards and Providing Examples

U.S. Patent Law requires that patent claims be sufficiently definite such that one of ordinary skill in the art could ascertain their metes and bounds.  Accused infringers may seek to invalidate claims under 35 U.S.C. § 112, ¶ 2 if the claims are not definite.  In considering such issues, the courts typically look at whether the claims are “insolubly ambiguous” and amenable to construction.

However, there is an aspect of indefiniteness that may not always be evident while preparing patent applications: ambiguity resulting from a failure to sufficiently specify the methods used to determine particular claim characteristics.  Inventors are not necessarily sensitive to this issue and may not think to flag it.  However, if the novelty of a claim depends on whether a particular property is present, it is important to determine what variables can affect the determination of the property.  Otherwise, an accused infringer will be able to argue that the scope of the claims is unclear.

Examples of Indefiniteness For Failure to Specify a Sufficiently Definite Calculation or Measurement Technique

In one case involving PET yarn production processes, the claims required a particular “melting point elevation” or “MPE.”  The patent defined MPE and even gave an example of how to determine it.  However, the method of preparing the sample to determine the MPE was not specified, and the sample preparation technique used by the inventors was actually a confidential company method.  As a result, the Federal Circuit court of appeals found the patent claims invalid for indefiniteness.  See Honeywell International, Inc. v. International Trade Commission, 341 F.3d 1332 (Fed. Cir. 2003).

Another case involved methods of using MRI to create images of nerves in the body. One of the claimed steps required determining “a conspicuity of the nerve that is at least 1.1 times that of adjacent non-neural tissue.”  While the patent disclosed techniques for measuring  “conspicuity” those techniques necessarily involved a subjective step of determining which part of an image is the “background” and which part is the “nerve.”  Although the court did not resolve the issue during claim construction, it did conclude that the defendant’s indefiniteness argument was “very persuasive” and indicated it would allow the defendant to pursue it.  Neurografix, et al.v. Siemens Medical Solutions, USA, Inc., et al., 2011 US Dist. LEXIS 89568 (C.D. Cal. 2011).

An additional example of this problem is described in Sandvik Intellectual Property AB v. Kennametal, Inc., 2012 US Dist. LEXIS 103169 (W.D. Pa. 2012).  In Sandvik, the patent in suit was directed to a coated cutting tool body with an alumina refractory layer having a certain “texture coefficient.”  The patent disclosed a formula for calculating the texture coefficient, but the patent provided no teaching as to how to select from among a variety of possible parameters that could be used to calculate one of the variables used to calculate the coefficient.  As a result, the court held the claims invalid for indefiniteness.

 Strategies for Avoiding Indefiniteness

Claims that recite particular physical properties or the calculation of specific values are potentially vulnerable to an indefiniteness attack if there is variability in how the properties or values may be determined.  Chemical or materials claims often raise these issues, in particular, because they often recite property values that can only be determined by test protocols.  Here are some key questions to address with the inventors to avoid this problem:

1)      Are there different formulas for calculating the relevant values? 

2)      Do the different formulas potentially yield different results?

3)      Which formulas do the inventors use in their work and why?

4)      Is there variability in the inputs to the formulas or in the way that test procedures may be carried out, and if so, what is the impact of the variability?

5)      Can the inventors supply specific examples of how they apply the formulas and methods that they use to calculate values recited in the claims?

6)      What would you do to determine if a competitor were using the invention?

7)      What would you do to determine if a piece of prior art disclosed the invention?

Based on the answers to these questions, the application can be drafted to clearly identify how to carry out  the relevant tests and calculations.  Adding specific examples that explain the details of the tests and calculations is well advised.  As discussed above, these types of indefiniteness issues may be difficult to anticipate, especially if the patent attorney is not deeply immersed in the specific technology and testing on which an invention is based.  However, answering these questions will help build a patent application that is less likely to be attacked as indefinite.