## Facts

- A patent issued in 1872 for a leather ball-cover construction using two hemispherical leather covers and a “double herring-bone” stitch; a second outer cover was added so the seams of the two covers crossed at right angles (“breaking joints”).
- The patent was assigned to Louis H. Mahn.
- In 1876, a reissue issued with claims broader than the original, emphasizing protection for the double-cover arrangement with breaking-joint seams.
- Mahn sued Harwood and other baseball manufacturers in equity in the U.S. Circuit Court for the District of Massachusetts, alleging infringement of the reissued patent by defendants’ double-covered baseballs.
- Defendants denied infringement and challenged validity, arguing lack of patentable novelty and that double-covered balls were made and used before the 1872 patent.

## Issues

1. Whether the reissued patent’s claims properly covered the double-cover, breaking-joint seam construction, or whether they impermissibly expanded beyond the original patent’s invention.
2. Whether prior manufacture or use of double-covered balls anticipated the patented combination or otherwise defeated novelty.
3. Whether defendants’ baseballs, as made and sold, infringed the reissued claims under the court’s construction.

## Decision

- The circuit court entered a decree for Mahn.
- The court treated the reissued patent as valid for purposes of the case.
- The court found that defendants’ double-covered baseballs infringed the reissued patent as construed.

## Legal Principles

- Patent infringement turns on construction of the asserted claims and comparison to the accused product’s structure and operation.
- A claimed combination is not anticipated unless prior art discloses the same combination; partial similarity or proof of earlier use that is not shown to match the claimed arrangement may be insufficient.
- In reissue litigation, a court may uphold and enforce a reissued patent where it views the reissue as consistent with the invention described and claimed, and not defeated by proven prior art, even when defendants argue the reissue broadened the original.

## Conclusion

The circuit court upheld the reissued patent covering a double-covered baseball construction with breaking-joint seams and special stitching, and it held that defendants’ similarly constructed baseballs infringed, awarding Mahn equitable relief.


Mahn v. Harwood, 16 F. Cas. 494 (C.C.D. Mass. 1878)