## Facts

- John Gonser invented and patented a meat-tenderizing machine and licensed the patent to Leland Detroit Manufacturing Company.
- The license required Leland to pay royalties and to assign to Gonser any “improvements or modifications” of the licensed “invention.”
- Leland manufactured the licensed machine but found it commercially unsatisfactory (including breakage of small blades and cleaning difficulties).
- While the license relationship still existed, Leland developed a different meat-tenderizing machine housed in a substantially similar outer structure.
- The new machine changed the internal mechanism by eliminating the patented gear-and-knife components and using a scissor-like roller action associated with earlier, known designs.
- Leland sought patent protection for the new design in its own name.
- Gonser sued for royalties and specific performance, seeking an आदेश compelling Leland to assign the new patent rights to him as an “improvement” under the contract.
- The trial court granted relief to Gonser, including specific performance of the assignment obligation.
- Leland appealed.

## Issues

1. Whether Leland’s later-developed machine was an “improvement or modification” of the licensed “invention” under the grant-back clause, requiring assignment to Gonser.
2. How “said invention” and “improvements” should be construed when the later device shares a general purpose and similar housing but omits the patented combination’s defining elements and uses mechanisms known in the prior art.
3. Whether specific performance was proper where the contract’s assignment duty depended on the disputed characterization of the later device as an “improvement.”

## Decision

- The Michigan Supreme Court reversed the trial court’s judgment.
- The court held Leland’s later machine was not an improvement or modification of Gonser’s patented invention within the meaning of the license.
- Because the grant-back clause was not triggered, Leland had no contractual duty to assign its later patent rights to Gonser.
- Specific performance was denied, and Gonser was not entitled to royalties based on Leland’s later machine.

## Legal Principles

- A grant-back clause covering “improvements or modifications” of a licensed “invention” is tied to the specific patented inventive combination, not the general field or commercial objective.
- An “improvement” must build upon, refine, or modify the patented concept; a later device that discards the patented combination and uses independent or prior-art principles is outside the clause.
- Similarity in function or external form does not, by itself, make a later device an “improvement” of the licensed invention.
- Specific performance to compel assignment is unavailable absent a clear contractual duty that applies to the technology at issue.

## Conclusion

The court construed the grant-back clause narrowly, holding it did not transfer rights in a later meat-tenderizing machine that abandoned the patented gear-and-knife arrangement and instead used a scissor-like mechanism known in the prior art; therefore, no assignment or related royalties were owed, and specific performance was improper.


Gonser v. Leland Detroit Mfg. Co., 293 Mich. 196, 291 N.W. 631 (Mich. 1940)