## Facts

- United States Pipe and Foundry Company (U.S. Pipe) and James B. Clow & Sons, Inc. (Clow) were competing manufacturers of cast-iron pressure pipe and push-on pipe joints.
- Yves Mathieu sought patent protection for a pipe-joint device, filing a first application in Brazil in 1955 and then a related U.S. application on May 25, 1956.
- On May 28, 1956, Lawrence Haugen and Carl Henrikson filed a U.S. application for a similar pipe-joint invention.
- The Patent Office declared an interference between Mathieu’s and Haugen/Henrikson’s applications to determine priority; Haugen and Henrikson were awarded priority.
- U.S. Patent No. 2,953,398 issued to Haugen and Henrikson and was assigned to U.S. Pipe.
- U.S. Pipe marketed its joint as the “Tyton-Joint.” Clow marketed its competing joint as “Bell-Tite.”
- U.S. Pipe sued Clow for infringement in the U.S. District Court for the Northern District of Alabama.
- Clow denied infringement and counterclaimed, asserting (among other defenses) that U.S. Pipe obtained or maintained the patent through fraud and that Mathieu, not Haugen and Henrikson, was the first inventor.
- Evidence before the district court included proof tending to show that Mathieu’s Brazilian disclosure differed materially from what was claimed in the issued ’398 patent.
- The district court held claims 1, 2, 4, 5, 7, and 8 of the ’398 patent valid and infringed and rejected Clow’s defenses and counterclaims; Clow appealed to the Fifth Circuit.

## Issues

1. Whether Clow proved that the ’398 patent was invalid or unenforceable due to fraud in the procurement of the patent or in connection with the interference proceeding.
2. Whether the ’398 patent was invalid because it was not issued to the first inventor, based on Mathieu’s earlier Brazilian filing and related U.S. application.
3. Whether the ’398 patent was invalid for lack of invention over the prior art and/or for failure to satisfy 35 U.S.C. § 112 (including alleged lack of specificity/definiteness in the claims and disclosure).
4. Whether Clow’s Bell-Tite joint infringed the asserted claims, including whether prosecution history (file-wrapper) estoppel or a narrow claim construction avoided infringement.

## Decision

- The Fifth Circuit affirmed the district court’s judgment for U.S. Pipe.
- The court upheld the rejection of Clow’s fraud allegations, finding the proof insufficient to establish fraud that would defeat the patent.
- The court upheld the determination that Clow failed to show the patent was issued to the wrong inventors; the interference award of priority to Haugen and Henrikson was not displaced on the record presented.
- The court sustained the district court’s findings that the asserted claims were patentable over the prior art and that the patent met the requirements of § 112.
- The court affirmed the finding of infringement, rejecting Clow’s arguments that the claims were so limited by prior art or prosecution history that Bell-Tite fell outside their scope.

## Legal Principles

- A duly issued patent carries a presumption of validity; the challenger bears the burden to prove invalidity.
- Claims of fraud on the Patent Office require strong proof of material misrepresentation or concealment with intent; mere disagreement with technical judgments made during examination or interference is not enough.
- A Patent Office interference priority award is not automatically binding in later infringement litigation, but it is entitled to substantial evidentiary weight; a party seeking to overturn the priority result must present convincing contrary proof.
- A first-inventor challenge requires proof that the asserted earlier work or filing discloses and supports the same invention as the issued claims; meaningful differences between an earlier foreign disclosure and the patented claims can defeat a priority-based invalidity defense.
- Validity challenges based on prior art depend on whether the claimed combination reflects more than what the art taught; secondary evidence such as performance advantages and market acceptance may support patentability when tied to the claimed features.
- Under 35 U.S.C. § 112, the specification and claims must describe the invention with sufficient clarity to inform skilled artisans of the bounds of the claims and how to make and use the invention.
- Infringement turns on proper claim construction and comparison to the accused device; prosecution history estoppel can limit a patentee’s ability to expand claim scope, but it applies only to subject matter actually surrendered during prosecution.

## Conclusion

The Fifth Circuit affirmed a judgment that U.S. Pipe’s ’398 push-on pipe-joint patent (Tyton-Joint) was valid and infringed by Clow’s Bell-Tite joint. Clow’s attacks based on alleged fraud, alleged first inventorship by Mathieu, prior art, and § 112 deficiencies failed, and the court declined to disturb the Patent Office’s interference award of priority to Haugen and Henrikson or to narrow the claims so far—by prior art or prosecution history—that infringement could be avoided.


James B. Clow & Sons, Inc. v. United States Pipe and Foundry Co., 313 F.2d 46, 136 U.S.P.Q. 397 (1963)