Last week, the Federal Circuit, in Forum US v. Flow Valve1, affirmed the lower court's ruling invalidating a reissue patent because the broadened claims added in the reissue failed to satisfy the original patent requirement under 35 U.S.C. § 251. As a brief refresher, the original patent requirement requires that a reissue patent shall only be granted "for the invention disclosed in the original patent."2

The Forum US decision offers helpful insight into how to draft applications with a sight toward future broadening reissues and provides practice pointers for those prosecuting broadening claims in a reissue application.


Flow Valve owns U.S. Patent No. RE45,878, a reissue of U.S. Patent No. 8,215,213. The invention relates to the machining of pipe joints to add threads, seats and other features. Specifically, the '213 patent discloses a "fixture" in which a pipe joint or workpiece is seated and which utilizes multiple removable arbors to fix the workpiece while it is machined by a machine tool.3

The '213 patent included three independent claims, each of which recited the "plurality of arbors" limitation. Moreover, the written description and drawings describe only a single embodiment, which includes the plurality of arbors. Even further, the '213 patent concludes by describing that the plurality of arbors "allows for rapid and accurate machining of the workpiece in a machine turning machine."

During prosecution of the reissue application, the applicant added seven broadened claims that did not recite the arbors, thereby broadening the claims.

The Reissue Litigation

On April 28, 2017, Forum US filed a declaratory judgment action seeking a declaration of invalidity of the reissue patent on the basis that the added claims do not comply with the original patent requirement. In support, Forum US argued that the reissue claims improperly broadened the original patent by failing to recite the arbor limitations because the original patent did not disclose or describe an invention without arbors.

Flow Valve contended that a person of ordinary skill in the art would have understood that the patent disclosed multiple inventions, including embodiments with and without arbors. Flow Valve did not dispute that the '213 patent does not specifically disclose an arbor-less embodiment; instead, Flow Valve relied on expert testimony from an experienced machinist, who opined that "a worker of ordinary skill would understand that not every fixture disclosed in the patent requires a plurality of arbors" and that "the arbors are an optional feature."4 The expert based his opinion, at least in part, on a generalized understanding "that numerous changes may be made which will readily suggest themselves to those skilled in the art which are encompassed within the spirit of the invention disclosed," as stated in the final paragraph of the '213 patent.5

Forum US moved for summary judgment of invalidity, which the district court granted. The district court held that the '213 patent does not "explicitly and unequivocally" disclose the new invention claimed in the reissue patent, citing Antares Pharma v. Medac Pharma.6 The district court further found that the expert testimony did not create a genuine issue of material fact because "no matter what a person of ordinary skill would recognize," the original patent requirement still mandates the clear and unequivocal disclosure of the newly claimed invention.7

The Federal Circuit affirmed the district court's decision, observing that the original patent "must do more than merely suggest or indicate the invention recited in reissue claims."8 Rather, the original patent "must clearly and unequivocally disclose the newly claimed invention as a separate invention."9 Looking to the face of the patent, the court was unpersuaded by both "references in the written description to machining in general that do not refer to or disclose specific embodiments" and "boilerplate language that modifications can be made."10

The Federal Circuit also agreed that Flow Valve's expert testimony was insufficient to create a genuine issue of material fact because it did not "aid the court in understanding what the instruments . . . actually say, but instead asserts what a person of ordinary skill in the art would purportedly understand in the absence of the disclosure of an arbor-less embodiment."11 The court therefore concluded that the original patent requirement could not be satisfied simply by demonstrating that a "person of ordinary skill in the art would understand that the newly claimed, arbor-less invention would be possible."12

The Forum US Takeaway

Fortunately for practitioners, the Forum US holding appears fact-specific and should not cause any lasting change to the original patent requirement. What can be gleaned from this decision is that our existing best practices—referring to various features as optional, using "may" throughout the specification, and describing alternative embodiments, however briefly, in which certain features are omitted or included—should carry weight in any reissue proceeding.

Here, the '213 patent specifically described an invention including arbors. A plain reading of the specification and review of the drawings did not reveal any indication that the inventors even considered an arbor-less embodiment at the time of the invention. Unsurprisingly, the court was unpersuaded by the patent owner's reliance on an expert testimony interpreting boilerplate language as describing what was invented. As is known, boilerplate language may provide for minor modifications or variations between the described embodiments but should not be relied upon to meaningfully or drastically enlarge the scope of the invention.

Thus, this opinion must be viewed in light of the facts: the original patent simply did not disclose or even reasonably contemplate a fixture without arbors, and the patent owner's attempt to broaden the patent by omitting the arbors based solely on boilerplate language and the corresponding expert testimony was unsuccessful.

If you would like to learn more, please contact Kyle Kellar at Chris Underwood, a non-lawyer summer law clerk, assisted Kyle Kellar in the preparation of this blog post. Kyle is the attorney responsible for all content.


1 Forum US, Inc., v. Flow Valve, LLC, ___F.3d___, 2019 WL 2494728 (Fed. Cir. June 17, 2019).

2 35 U.S.C. § 251(a) (emphasis added).

3 Forum US, Inc., ___F.3d___, 2019 WL 2494728 at *2.

4 Id. at *3 (internal quotations omitted).

5 Id.

6 Id. at *2, citing Antares Pharma, Inc. v. Medac Pharma Inc., 771 F.3d 1354 (Fed. Cir. 2014).

7 Id.

8 Id. at *4.

9 Id.

10 Id.

11 Id., citing Indus. Chems., Inc. v. Carbide & Carbon Chems. Corp., 315 U.S. 668, 678 (1942).

12 Id.

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