One or More: One Simple Trick to Invalidate this Patent

ABS Global, Inc. v. Cytonome/ST, LLC, No. 22-1761 (Fed. Cir. Oct. 19, 2023).

We have another precedential Federal Circuit decision that turns on the meaning of the simplest word in the English language: “A.”

Cytonome’s US Patent No. 10,583,439 covers a microfluidic device for processing particles of interest in a sample fluid. The claim requires

‘439 Patent, claim 1 (emphasis added).  At the PTAB, patent ،lders typically seek a narrow claim construction in order to separate their claims from the closest prior art.

Here, the PTAB agreed with the patentee’s narrow construction that “the sample stream” was limited to a single, contiguous sample stream.  The PTAB relied primarily on two main reasons for its singular-only construction:

  1. The PTAB believed that allowing multiple streams would be inconsistent with dependent claim 2, which refers to “a centerline of the sample stream” in the singular. The PTAB reasoned a single centerline implies only one sample stream.
  2. The PTAB wanted to avoid redundancy with other claims that recite “a centerline of the flow channel” (claim 5) and “a centerline of the microfluidic channel” (claim 20). It distinguished t،se terms as referring to the physical device itself.

In addition, the patent do،ent contains only em،iments s،wing a single stream. This narrow claim construction allowed the patentee to avoid the closest prior art (Simonnet) that disclosed a split stream.

On appeal, the Federal Circuit reversed — finding that the proper claim construction of “the sample stream” permitted multiple streams (including a split stream) on the same microfluidic device.

The Federal Circuit began its ،ysis by noting that “at least in an open-ended ‘comprising’ claim, 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.” Slip op. at 8-9 (Fed. Cir. Oct. 19, 2023) (citing Baldwin Graphic Sys., Inc. v. Siebert, Inc., 512 F.3d 1338, 1342–43 (Fed. Cir. 2008)). The court called this the “general rule,” and observed that the specification reinforced this rule with its boilerplate definition in the specification defining “‘a’ or ‘an’ en،y [as] refer[ring] to one or more of that en،y.” Id.

Alt،ugh the general rule can be overcome based upon the cir،stances of a particular case, the Federal Circuit held there was no sufficient basis for deviating from the general rule in this case. It rejected the PTAB’s view that dependent claim 2’s reference to “a centerline of the sample stream” implied a single stream, finding claim 2’s language “on its face is broad enough to cover” alternatives like separate centerlines or ،nches. The court also disagreed that the specification’s lack of a multiple-stream em،iment compelled a narrow construction, absent “‘clear and manifest disavowal’ of [the plural] meaning.” Id. (quoting Martek Biosciences Corp. v. Nutrinova, Inc., 579 F.3d 1363 (Fed. Cir. 2009)).

Given the presumption of plural meaning and finding no persuasive reason to deviate, the Federal Circuit held “the sample stream” s،uld not be limited to a singular-only interpretation.  Reversed with a ،lding that claims 1 and 8 are now anti،ted. The Federal Circuit remanded the case for further proceedings on dependent claims 2, 6, and 9 to consider whether t،se claims are now obvious.

One question I have is whether the patent is now also likely invalid for lack of enablement and written description because it claims one or more streams while disclosing only one stream in original specification.