Claim term “at least one component of [a unit]” excludes the entire unit – expert testimony cannot override intrinsic evidence

Nicolas Seckel | April 17, 2015

Enzo Biochem Inc. v. Applera Corp. (Precedential)

March 16, 2015

Before: Prost, Newman and Linn. Opinion by Prost, Dissent by Newman.


In this case, grammatical construction and invention “purpose” beat expert testimony and claim differentiation, leading to reversal of the District Court’s claim interpretation.

One might have thought that the Federal Circuit would make a point of carefully applying the different standards of review when a District Court’s claim construction relied in part on extrinsic evidence (“clear error” for findings based on extrinsic evidence, instead of “de novo” review for intrinsic evidence, see Teva Pharm. USA, Inc. v. Sandoz, Inc. (Jan. 20, 2015)).

This decision suggests a different trend, toward minimizing the importance of extrinsic evidence in claim interpretation, which allows the Federal Circuit to maintain its customary high level of scrutiny.


Patentee Enzo Biochem sued Applera in 2004 for infringement of several patents.  After a summary judgment, a first appeal, a remand and a trial, this is the second appeal.  Enzo’s 767 patent is at issue in this second appeal.  The technology is DNA sequencing; the patent focuses on a new class of detectable molecules to replace the radioactive isotopes which are used as DNA probes in the conventional technique.

Representative claim 1 is as follows:

1.   An oligo- or polynucleotide containing a nucleotide having the structure:

[ ]-B•••A

…wherein A… represents at least one component of a signaling moiety capable of producing a detectable signal;

… wherein… a linkage group [•••]… does not substantially interfere with the formation of the signaling moiety or detection of the detectable signal…

The issue is whether A covers a chemical group that can produce a detectable signal (direct detection), or only a non-signaling portion that must link to a signaling portion (indirect detection).

The District Court interpreted A as covering both direct and indirect detection.

Judge Prost focuses first on the claim language.  She explains that the expression “at least one component” is necessarily limited to a portion of a multipart system, otherwise “component of a signaling moiety” would have no meaning.  The expression “at least one component” used here is different from the typical clause “at least one element” because the term “component” requires several “components, at least one of which is ‘A.’”

Judge Prost finds additional support for her analysis throughout the description, since the background, general presentation, and main embodiments focus on A being a nucleotide derivative that links to avidin or antibodies to form a signaling moiety, and the description emphasizes the advantages of indirect detection over radioactive labeling, a direct detection method.

Enzo argued that its expert had established the direct detectability of various A groups mentioned in the description, but this testimony concerned the detection of A in isolation, not when linked to the B-nucleotide.  Also, based on expert testimony, the District Court had concluded that example 9 in the description performed direct detection, but Judge Prost finds that “this sole factual finding does not override our analysis of the totality of the specification, which clearly indicates that the purpose of this invention was directed towards indirect detection, not direct detection.”

Finally, the District Court had relied on the fact that some dependent claims involved direct detection (for example, claim 67 directed to “[a]n oligo- or polynucleotide of claim 1 or 48 wherein A comprises an indicator molecule”), but the doctrine of claim differentiation cannot be used to broaden a claim that is limited to indirect detection “by its own plain meaning.”

In dissent, Judge Newman would have accepted that a “component” may form an entire detectable unit, and she would have given deference to the District Court’s reliance on expert testimony regarding example 9 of the description.


Practitioners beware of terminology that indicates or implies a discrete numbering or dichotomy.  The interpretation of “component” as excluding the whole unit in this case recalls the formalistic approach in Moore U.S.A., Inc. v. Standard Register Co., 229 F.3d 1091, 1106. (Fed. Cir. 2000). (claim term “majority” excludes “minority,” so 47.8% cannot be an equivalent).

This decision also shows that, Teva notwithstanding, involving an expert in claim interpretation will not necessary tip the balance, let alone insulate the District Court’s claim interpretation from reversal on appeal.  The Federal Circuit will keep on giving more weight to intrinsic evidence, especially the claim language itself and the purpose of the invention set forth in the specification.

Full Opinion

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