When does “A” mean more than one?

The Federal Circuit has reversed a claim construction adopted during an inter partes review (IPR) because the Patent Trial & Appeal Board (PTAB or Board) erred in construing the limitation “a” to mean a single sample rather than including the possibility of multiple samples.

The case is ABS Global, Inc. v. Cytonome/ST, LLC.

Cytonome/ST owns U.S. Patent No. 10,583,439, which describes and claims a microfluidic device for use in processing particles (such as cells and molecules) contained in a sample fluid.

As the court explained,

Under certain conditions, if one fluid is introduced into a microchannel and then a second fluid is introduced into the same microchannel, the two fluids travel in “laminar flow,” i.e., in parallel layers (which may, for example, be horizontally or vertically aligned), without mixing. … “Sheath flow” is a type of laminar flow in which a layer of “sample fluid” that contains particles is abutted on more than one side by a layer of particle-free sheath fluid.

Independent claim 1 of the ’439 patent claims a microfluidic device configured to focus sample fluid:

A microfluidic assembly for use with a particle processing instrument, the microfluidic assembly comprising:

a substrate;

and a flow channel formed in the substrate, the flow channel having:

an inlet configured to receive a sample stream;
a fluid focusing region configured to focus the sample stream…

(Emphasis added by court.)

The patent’s specification includes the following definition:

[F]or the purposes of the present disclosure, the term ‘a’ or ‘an’ entity refers to one or more of that entity. As such, the terms ‘a’ or ‘an’, ‘one or more’ and ‘at least one’ can be used interchangeably herein.

ABS petitioned the US Patent and Trademark Office (USPTO) for an inter partes review, under 35 U.S.C. §§ 311–19, of the patentability of claims 1, 2, 6, 8, and 9 of the ’439 patent.

Inter partes review, as the USPTO explains, is a relatively new trial proceeding conducted at the Board to review the patentability of one or more claims in a patent only on a ground that could be raised under 35 U.S.C. §§ 102 or 103.

Under 35 U.S. Code § 102, a person is entitled to a patent unless:

1. the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention; or
2. the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.

Under 35 U.S. Code § 103,

A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains.

The inter partes review process begins with a third party (a person who is not the owner of the patent) filing a petition after the later of either:

1. 9 months after the grant of the patent or issuance of a reissue patent; or
2. if a post-grant review is instituted, the termination of the post-grant review.

An inter partes review may be instituted upon a showing that there is a reasonable likelihood that the petitioner would prevail with respect to at least one claim challenged.

ABS argued that the claims were unpatentable for anticipation and/or obviousness based on three prior art references.

“Anticipation” refers to the prior invention or disclosure of the claimed invention by another, or the inventor’s own disclosure before the application for the patent.

“Obviousness” means that someone of ordinary skill in a relevant field could easily make the invention.

(Possible objective indications of nonobviousness, as Cornell Law School notes, could include commercial success, initial skepticism regarding the invention, and demonstrated failure of others to solve a long-standing problem.)

The PTAB granted the petition and determined that ABS had not shown any of the challenged claims to be unpatentable.

The Board held that ABS had not proved any of the challenged claims to be unpatentable because one prior art reference failed to disclose one claim limitation—specifically, “the sample stream” component of the “fluid focusing region” element. The Board determined that, as a matter of claim construction, “the sample stream” language in claim 1 had a singular-only meaning, not allowing a plurality of streams or a split stream.

The Board also rejected ABS’s obviousness challenges, based on the claim construction that claim 1 required that there be only a single stream, precluding a split one.

ABS appealed.

The Federal Circuit agreed with ABS’s principal contention—that the Board erred in its claim construction of a limitation common to all challenged claims.

The court noted that

The specific claim language at issue is “a fluid focusing region configured to focus the sample stream.” The use of the definite article, “the,” means that the phrase “the sample stream” refers back to earlier language as an antecedent. The antecedent language is “a sample stream” in the preceding limitation, and it is the singular-only or plural allowing meaning of that limitation which is determinative. The reference-back “the” language takes its meaning from the meaning of the antecedent, so if “a sample stream” has a plural-allowing meaning, so does the reference-back “the sample stream” phrase.

Claim-construction analysis, said the court, supported the plural-allowing meaning.

First, “at least in an open-ended ‘comprising’ claim,” like claim 1 of the ’439 patent, “use of ‘a’ or ‘an’ before a noun naming an object” requires that the phrase be construed to mean “‘one or more’ unless the context sufficiently indicates otherwise.”…

Second, the specification here states: “[F]or the purposes of the present disclosure, the term ‘a’ or ‘an’ entity refers to one or more of that entity. As such, the terms ‘a’ or ‘an’, ‘one or more’ and ‘at least one’ can be used interchangeably herein.”

Said the court:

That definition reinforces, rather than negates, the applicability here of the “one or more” general rule concerning “a” or “an.” It also brings into play the lexicography principle—that, with narrow exceptions, “[w]here the specification instructs as to the meaning of a claim term, ‘the inventor’s lexicography governs.’”

Thus, the court reversed in part, vacated, and remanded.