## Facts

- Republic Industries, Inc. owned U.S. Patent No. 3,852,845 (the Slaybaugh patent) covering an electrically controlled hydraulic door closer/holder used on emergency exit doors.
- The claimed device combined a spring-and-piston hydraulic door closer with a solenoid-actuated valve that could hold a door open at multiple positions and permit “momentary manual release” of the hold-open function.
- Republic sued Schlage Lock Company, alleging infringement of claims 8 and 9 based on Schlage’s LCN door closer/holder product.
- Schlage denied infringement and counterclaimed, seeking a declaration that the asserted claims were invalid, principally as obvious under 35 U.S.C. § 103.
- At trial, Schlage relied in part on prior-art references that had not been considered by the Patent and Trademark Office during prosecution.
- The district court held the asserted patent claims invalid as obvious and, because of invalidity, did not decide infringement.
- Republic appealed the invalidity judgment.

## Issues

1. Whether the asserted claims of the Slaybaugh patent were invalid as obvious under 35 U.S.C. § 103 when evaluated under the *Graham v. John Deere* framework.
2. What effect prior-art references not considered by the Patent and Trademark Office have on the statutory presumption of validity under 35 U.S.C. § 282.
3. Whether “synergism” is a controlling, independent requirement for validity of a combination patent.

## Decision

- The Seventh Circuit affirmed the judgment that the asserted claims were invalid for obviousness under 35 U.S.C. § 103.
- The court treated previously unconsidered prior art as diminishing the force of the presumption of validity.
- The court rejected “synergism” as an independent statutory test and evaluated validity under the § 103/*Graham* analysis.
- Because the patent was invalid, the court found it unnecessary to reach infringement.

## Legal Principles

- A patent is presumed valid under 35 U.S.C. § 282, but the presumption is not conclusive and shifts the burden of proof to the challenger.
- The presumption of validity carries reduced force when the challenger produces material prior art that was not before the Patent and Trademark Office; even a single such reference may be sufficient to overcome the presumption.
- Obviousness under 35 U.S.C. § 103 is determined by the *Graham* factors: (1) scope and content of the prior art, (2) differences between the prior art and the claims, and (3) the level of ordinary skill in the art.
- The § 103 inquiry is not whether the claimed invention is “equivalent” to a prior-art element, but whether the differences from the prior art are sufficient to render the claim nonobvious to a person of ordinary skill.
- For combination patents, “synergism” is not a standalone legal requirement; validity turns on the statutory § 103 analysis, with the expected operation of combined known elements weighing toward obviousness.

## Conclusion

The Seventh Circuit held the Slaybaugh door closer/holder claims invalid as obvious because the asserted advance was a combination of known hydraulic and electrical components with only small, predictable differences from the prior art, and previously unconsidered prior art further weakened the patent’s presumption of validity; as a result, infringement was not addressed.


Republic Indus., Inc. v. Schlage Lock Co., 592 F.2d 963 (7th Cir. 1979)