## Facts

- Inventors filed a U.S. patent application (Serial No. 543,520) directed to highly active ethylene polymerization catalysts, including titanium-based Ziegler catalysts dispersed on activated anhydrous magnesium dihalide supports, as well as related preparation and polymerization process claims.
- The PTO examiner finally rejected claims 17–34 for obviousness-type double patenting over claims in three commonly owned copending applications, relying additionally on four patents to others as evidence that any differences were obvious.
- The PTO Board of Appeals affirmed the double patenting rejection.
- The inventors appealed to the U.S. Court of Appeals for the Federal Circuit, arguing their claims were patentably distinct and not barred merely because related applications existed under common ownership.

## Issues

1. Whether claims 17–34 were unpatentable for obviousness-type double patenting over claims in three commonly owned applications.
2. Whether, in assessing patentable distinctness for obviousness-type double patenting, the PTO could consider additional prior art patents to determine whether the later claims were merely obvious variations.
3. Whether non-identical claim language and asserted differences in catalyst structure and support activation established patentable distinctness.

## Decision

- The Federal Circuit affirmed the Board’s decision.
- The court held that claims 17–34 were properly rejected for obviousness-type double patenting over the claims of the three commonly owned applications, as informed by the four additional prior art patents.
- The court agreed that the later-claimed catalyst subject matter constituted an obvious variation and was not patentably distinct from what was already claimed in the related applications.

## Legal Principles

- Obviousness-type double patenting is a judicial doctrine that bars multiple patents that would effectively extend exclusivity through claims that are obvious variations of earlier claimed inventions under common ownership or control.
- The patentable distinctness inquiry compares the later claims to the earlier claims; differences in claim wording do not avoid double patenting if the later subject matter would have been obvious over the earlier claimed invention.
- In evaluating obviousness-type double patenting, the PTO may use relevant prior art to assess whether the differences between claim sets would have been obvious to a person of ordinary skill in the art.
- Common ownership does not justify separate patents for closely related chemical compositions or methods when the later claims add only obvious modifications.
- A terminal disclaimer may address term-extension concerns when claims are otherwise patentable, but it does not supply patentability where the later claims are not patentably distinct.

## Conclusion

The Federal Circuit upheld the PTO’s obviousness-type double patenting rejection, concluding that the later catalyst claims were not patentably distinct from commonly owned claims and that additional prior art could be considered to confirm that the asserted differences were obvious.


In re Longi, 759 F.2d 887 (Fed. Cir. 1985)