The Federal Circuit’s decision in Global Tubing LLC v. Tenaris Coiled Tubes LLC, No. 2023-1882 (Fed. Cir. Feb. 26, 2026) delivers a sharp reminder that even apparently damning internal language will not short-circuit the demanding standards governing inequitable conduct and Walker Process fraud. In its opinion, the court vacated summary judgment of inequitable conduct and likewise vacated summary judgment of no liability on a related antitrust claim, holding that genuine disputes of material fact precluded judgment as a matter of law on both issues.
At the center of the controversy was an inventor’s margin comment during prosecution: “I am not sure it is a good idea to disclose this document.” The district court viewed that statement as rare direct evidence of intent to deceive the PTO and declared the patents unenforceable on summary judgment. The Federal Circuit disagreed—not because the evidence was weak, but because the summary judgment standard is unforgiving when credibility and competing inferences are in play.
Charles Gideon Korrell believes this decision reinforces a broader theme in post-Therasense jurisprudence: courts remain wary of resolving inequitable conduct on paper, especially where intent turns on how one interprets a single ambiguous remark in a complex prosecution record.
The CYMAX Documents and Overlapping Carbon Ranges
The technology involves quenched-and-tempered coiled tubing used in oil and gas wells. In the 1990s, Southwestern Pipe developed “CYMAX,” a product manufactured using a quench-and-temper process. Tenaris later acquired Southwestern’s assets, including internal “CYMAX Documents” describing the process and chemical composition.
Tenaris eventually obtained U.S. Patent Nos. 9,803,256, 10,378,074, and 10,378,075 covering its own quenched-and-tempered product, “BlueCoil.” Claim 1 of the ’256 patent recites a coiled steel tube with, among other limitations, 0.17–0.35 wt.% carbon and yield strength greater than about 80 ksi.
The CYMAX Documents disclosed a carbon range of 0.13–0.17 wt.% and a yield strength of 100 ksi. The overlap at 0.17 wt.% proved pivotal. Under In re Geisler, prior art ranges that “touch” a claimed range can support a prima facie case of obviousness.
Tenaris submitted a 1992 Chitwood conference paper to the PTO, which described CYMAX as using “low-carbon 4100 series steel” with 100 ksi yield strength, but did not disclose the specific 0.13–0.17 wt.% carbon range found on page 30 of the internal CYMAX Documents. The internal documents themselves were not provided during prosecution of the ’256 patent.
The prosecution record became more complicated in later continuations and divisionals. For the ’074 and ’075 patents, Tenaris submitted the CYMAX Documents only in fragmented form and omitted the critical pages containing the specific carbon range. Only during prosecution of later “grandchild” applications did Tenaris finally submit the full set, including page 30.
Inequitable Conduct After Therasense
The legal framework is well-settled since Therasense, Inc. v. Becton, Dickinson & Co. To prevail, an accused infringer must prove by clear and convincing evidence that a specific individual:
- Knew of the reference,
- Knew it was material, and
- Made a deliberate decision to withhold it.
Materiality requires “but-for” proof: the PTO would not have allowed the claim had it been aware of the undisclosed reference. Prior art is not but-for material if it is merely cumulative.
The district court concluded that the inventor’s “not sure it is a good idea” comment was effectively a confession of deceptive intent. The Federal Circuit, however, emphasized that summary judgment requires drawing all reasonable inferences in favor of the nonmovant.
Here, competing inferences existed:
- One inference: the inventor knew of the overlapping 0.17 wt.% endpoint and sought to hide a reference that would doom the claims.
- Alternative inference: the inventor mistakenly believed the carbon ranges did not overlap, thought CYMAX reflected a “lower carbon” approach distinct from the claimed invention, and believed Chitwood already conveyed the relevant information.
The appellate court stressed that even if the inventor was factually and legally wrong about overlap, a mistaken understanding does not automatically equate to specific intent to deceive. Credibility determinations belong at trial, not at summary judgment.
Charles Gideon Korrell notes that this aspect of the opinion underscores the enduring force of Therasense’s “single most reasonable inference” test. When the record plausibly supports an innocent explanation—even a flawed one—inequitable conduct rarely can be resolved without live testimony.
The Cumulative Reference Dispute
Materiality presented a separate factual dispute. Tenaris argued that Chitwood, which referenced “low-carbon 4100 series steel” and ASTM specifications, would have enabled a skilled artisan to discern the same chemical composition found in the CYMAX Documents.
If Chitwood was cumulative, the withheld documents were not but-for material. The district court rejected this theory. The Federal Circuit held that a reasonable factfinder could accept it, especially given expert testimony and evidence that ASTM tables could supply the missing chemistry details.
The court also pointed to the prosecution of later “grandchild” applications, in which the full CYMAX Documents were submitted and the PTO still allowed claims (albeit after amendment). While not dispositive, that sequence could support an inference that disclosure would not have changed the outcome for the earlier patents.
Charles Gideon Korrell believes this portion of the opinion highlights a strategic takeaway: where related applications have been examined with fuller disclosures, that record may later become critical evidence in defending against inequitable conduct claims.
Walker Process and the “Small Market Player” Problem
Global Tubing also asserted a Walker Process claim under Walker Process Equipment, Inc. v. Food Machinery & Chemical Corp., alleging that Tenaris attempted to monopolize the market by asserting fraudulently obtained patents.
To prevail, a plaintiff must show both fraud on the PTO and satisfaction of all elements of attempted monopolization under § 2 of the Sherman Act, including:
- Anticompetitive conduct,
- Specific intent to monopolize, and
- A dangerous probability of achieving monopoly power. Spectrum Sports, Inc. v. McQuillan
The district court granted summary judgment to Tenaris, reasoning that as a “small market player” with roughly 29% market share, Tenaris could not, as a matter of law, pose a dangerous probability of monopolization.
The Federal Circuit rejected that categorical approach. Market definition—both product and geographic—is a fact question. Competing expert testimony addressed whether the relevant market was:
- U.S. quenched-and-tempered coiled tubing only (Global’s view), or
- The global market for all coiled tubing products (Tenaris’s view).
Without resolving those disputes, the district court could not conclude that 29% share was legally insufficient. Citing Fifth Circuit precedent, the panel reiterated that attempted monopolization does not require majority market share; other structural factors may suffice.
The record also included evidence that Tenaris allegedly told customers it would likely sue Global Tubing and characterized DURACOIL as a “copycat.” A reasonable factfinder could treat those actions as anticompetitive conduct tied to allegedly fraudulently obtained patents.
Charles Gideon Korrell observes that this portion of the ruling may embolden Walker Process plaintiffs in cases where market share is below 50% but the asserted patents cover a narrowly defined, technology-specific niche.
What Comes Next
The case returns to the district court for further proceedings. Both inequitable conduct and Walker Process fraud may proceed to trial, potentially with overlapping fact questions concerning intent and materiality.
The practical lesson is clear: even a statement that appears to be a “smoking gun” does not eliminate the need for a trial where competing inferences and credibility are at stake. The Federal Circuit continues to guard against the overuse of inequitable conduct as a litigation weapon, insisting that the Therasense standard be applied rigorously at every procedural stage.
Charles Gideon Korrell believes the opinion is also a reminder that prosecution decisions made years earlier—especially decisions about what not to submit—can reverberate not only through enforceability but also into antitrust exposure.