Give me a number, any number


Give me a number, any number

by Kenneth J. Weatherwax and Flavio M. Rose

The United States Supreme Court has granted a writ of certiorari this term in Nautilus, Inc. v. Biosig Instruments, Inc. (reviewing the Court of Appeals’ decision in Biosig Instruments, Inc. v. Nautilus, Inc., 715 F.3d 891 (Fed. Cir. 2013)), to address the legal test for when a United States patent claim is invalid for “indefiniteness.”  Because disputes over the definiteness of patent claims are fairly common, the Supreme Court’s forthcoming decision might have an effect on many patent claims.

United States patent claims must “particularly point [..] out and distinctly claim[..] the subject matter which the inventor or a joint inventor regards as the invention.”  35 U.S.C. § 112.  Patent applicants seek to draft claims that will both satisfy this requirement—referred to as “definiteness”—and also cover and protect the full scope of the invention’s subject matter.  In doing, choices often arise as to how narrow or broad, or precise, the language of the claim should be.

It is common in patent claim drafting to use adjectives of degree.  Such claim terms are often not accompanied by any nume­ri­cal value, even though such a value, had it been used, would have given the claim greater preci­sion.  A simple example of this is the adjective “conductive.”  The electrical conduc­tivity of mate­rials varies over many orders of magnitude and can be measured readily in, say, inverse ohm-cm.  Where a patent attorney writes in a claim “an electrically conductive X,” he might sometimes, depending on the circumstances, have written more precisely “an X having a conductivity of at least y (ohm-cm)–1.”

Suppose that the patent attorney declined to use the more precise formu­lation and the American patent office finds the claim allowable without object­ing.  The patent issues and is asserted in litigation.  The patent claim then has to be compared to an accused product having an X to see if that X is “conduc­tive.”  What should a court do?  There are many options.  Two are:

(a) the judge, in the claim cons­truction phase of the lawsuit, might decide that “conductive” means “having a conduc­ti­vity of at least y (ohm-cm)–1” (picking a y in the process), or

(b) the judge might have the jury decide, based on compe­ting expert testimony, whether the accused product’s X is conduc­tive or not.  The jury might, for example, decide that one expert is believable and the other is not, based on their assessment of the persuasiveness of each expert’s scientific argument, perhaps influenced also by each experts’ demeanor on the stand, how firmly each resisted cross-examination, which has the more prestigious professorship, or other such facts.

Both of these options have caselaw support.

For example, in Johns Hopkins University v. Cellpro, Inc., 152 F.3d 1342 (Fed. Cir. 1998), the claims required an infringing product to be “substan­tially free” of a particular class of impurities.  That requirement was inter­preted to mean “no more than 10%” of those impurities.  This criterion was an impurity level that was disclosed in the patent specification, but that was not set forth explicitly in the claims.

Other examples of numerical claim constructions include the following:

  • Arcelormittal France v. AK Steel Corp., 700 F.3d 1314 (Fed. Cir. 2012), interpreted the claim term “very high mechanical resis­tance” to mean a mechanical resistance of at least 1500 MPa.  The patent specification stated that under the invention “it is possible to obtain high mechanical charac­te­ristics which may exceed 1500 MPa for mechanical resistance and 1200 MPa for the limit of elasti­city.”  A dissenting judge would have preferred a construction specifying 1000 MPa instead of 1500 MPa.  (In this case, “mechanical resistance” meant, it appears, ultimate tensile strength.)
  • Oakley, Inc. v. Sun­glass Hut International, 316 F.3d 1331 (Fed. Cir. 2003), interpreted the claim term “vivid colored appearance” to mean that “the maxi­mum differential effect equal[s] or exceed[s] about 5.45%.”  Here, “differential effect” was a quantity that was defined in the specification and that depended on both a reference intensity and a wavelength, as well as on a measured intensity of light reflected in the accused product.
  • Glaxo Group Ltd. v. Ranbaxy Pharmaceuticals, Inc., 262 F.3d 1333 (Fed. Cir. 2001), found that the term “‘essen­tially free from crystalline material’ meant a maximum crystalline content of less than 10%.”
  • Key Pharmaceuticals v. Hercon Laboratories, 161 F.3d 709, 718 (Fed. Cir. 1998), gave the term “a pharmaceutically acceptable amount” the meaning of 2.5 mg/day, referring to FDA publica­tions.

There are of course other cases which have refused to give adjectives in claims a nume­­rical value when construing them.  For example, Ekchian v. Home Depot Inc., 104 F.3d 1299 (Fed. Cir. 1997), declined to read the term “conducting” to mean having at least the lowest numerical value for conductivity disclosed in the specification, and instead adopted a nonnumerical construction that (at least arguably, in the circumstances of the case) read the term effectively out of the claims by taking it to mean suf­fi­ciently conduc­tive for the invention to work.

Other cases declining to impose numerical claim constructions include the following:

  • In Leo Pharmaceutical Prods. v. Rea, 726 F.3d 1346 (Fed. Cir. 2013), the Patent and Trademark Office felt the need to define “storage stable” by specifying the num­ber of days of stability which was required at a particular temperature, using a stability test disclosed in the specification.  The Federal Circuit, however, disagreed, saying that such a meaning was “far short of [the term’s] broadest reasonable mean­ing.”
  • Aventis Pharmaceuticals v. Amino Chemicals, Inc., 715 F.3d 1363 (Fed. Cir. 2013), reversed the district court’s construction of “subs­tan­tially pure” as no more than 2% impurities, a construction based on the prosecution his­tory, and instead preferred “largely but not wholly pure,” in part because it was “faithful to the specifica­tion’s silence regarding numerical preci­sion.”

When may a claim be construed to give a nonnumerical term a numerical meaning?  This recurring issue is now before the Supreme Court in Nautilus  The Supreme Court has granted certiorari in Nautilus to address, in part, the question “[w]hether the Federal Circuit’s acceptance of ambiguous patent claims with multiple reasonable interpretations – so long as the ambiguity is not ‘insoluble’ by a court – defeats the statutory requirement of particular and distinct patent claiming.”

In Nautilus, the accused technology is a device to measure a person’s pulse based on their grasping a cylinder with their hand.  These devices are common in gym equipment such as treadmills and elliptical trainers.  The claim at issue recite that this cylinder must have two electrodes “in spaced relationship.”  The phrase “in spaced relationship” is widely used in American patents, often to convey a meaning that two things are spaced apart from each other; according to a search of the Patent and Trademark Office’s database, tens of thousands of United States patents use such language.

The district judge decided on summary judgment that the Nautilus claims were indefinite because no particular spacing or range of spacings between the two electrodes was given.  In this, he was following in the footsteps of many judges in other cases who have expressed the wish that the patent claims before them contained a number that would facili­tate the determination of infringement or non-infringement.  Finding the claims indefinite, the judge declared them invalid, giving the accused infringer a victory.

In contrast, on appeal the Federal Circuit thought it was acceptable not to have a numerical spacing or range of spacings in the claim.  Biosig, 715 F.3d at 901-03.  The panel majority explained that “we have not insisted that claims be plain on their face in order to avoid a determination of invalidity for indefiniteness,” id. at 901; rather, in construing a claim, “[w]hen a word of degree is used, the court must determine whether the patent provides some standard for measuring that degree,” id. at 898.  In this case, the majority said, “certain inherent parameters” in the intrinsic evidence provided a sufficient standard for persons of ordinary skill in the art to determine when accused instrumentalities were “in spaced relationship” as required.  Id. at 899  A declaration by the inventor presented by the paten­tee in reexamination had suggested a detailed procedure for deter­mi­ning what electrode spacings would work well.  Id. at 900.  The declaration, having been presented to the PTO, became part of the prosecution history and thus, as is often the case in American law, was held to merit being taken into account in construing the term “in spaced relationship.”  Id.  Having approved the use of this decla­ra­tion to construe the term, the Fede­ral Circuit majority found that the claim was not invalid for indefi­niteness, and so the case had to go back to the district court for trial.  Id. at 904-05.  (The third judge on the panel effectively concurred in the judgment based “on a more limited analysis.”)

In the Supreme Court, the accused infringer sought and received a writ of certiorari to review a dra­ma­tically worded question: should patent claims be found indefi­nite, and thus inva­lid, whenever they have “mul­ti­ple reasonable interpretations”?  The reason that this is a rather dramatically put question in this instance is that adjectives like “in spaced relationship” (and “conductive” and “substantially free”) are just one of a number of types of claim terms that can have multiple reasonable interpretations.  If common, poten­tially ambiguous ways of phrasing claim limitations, currently present in untold thousands of issued claims, were to be suddenly ruled out, the implications would be revolutionary.  Many existing patent claims might become invalid.  Patent attorneys might have to begin work on an entire new generation of patents with claims that are drafted in new or different ways than in the past.  It there­fore seems unlikely that the Supreme Court’s coming decision in Biosig could require patent drafters to write without any ambi­guity of any type, as the accused infringer is seemingly requesting.

Assuming the Supreme Court does not go that far, even if it reverses the Federal Circuit, it may well state a rule at a higher level of generality.  The Federal Circuit has said that for a claim to be indefinite it must be “insolubly ambiguous,” and that “[a]n ungainly claim is not thereby indefinite, when its meaning can be understood by a person experienced in the field of the invention, on review of the patent documents.”  Funai Elec. Co., Ltd. v. Daewoo Elecs. Corp., 616 F.3d 1357, 1372 (Fed. Cir. 2010).  The Federal Circuit has also stated that a claim cannot be indefinite if it is “amenable to construc­tion, how­ever difficult that task may be.”  Exxon Research & Engineering Co. v. United States, 265 F.3d 1371, 1375 (Fed. Cir. 2001).  Perhaps the Supreme Court will be content with disapproving or adjusting some of these rather demanding-sounding verbal formulations, substituting a softer formulation of its own, and vacating to let the Federal Circuit sort out the application of the new test to the situation at hand.

Alternatively, however, the Supreme Court may dig down and consider whe­ther not specifying the spacing with more precision constituted excessive vagueness on this paten­tee’s part.  A “yes” answer to even that limited ques­tion might also cause significant tremors in the world of American patents.  Perhaps, however, the Jus­tices’ ins­tincts are dif­fe­rent from those of Federal Circuit judges, and more aligned with that of the district judge in this case, who felt strongly—to judge by his ruling from the bench—that a number, any number, was needed.

Oral argument in Nautilus is slated to occur on April 28.

Flavio Rose, Lowenstein & Weatherwax LLP and Bandgap Engineering
Kenneth J. Weatherwax, Lowenstein & Weatherwax LLP


Published March 18, 2014