## Facts

- Kalo Inoculant Co. owned a patent claiming mixed cultures of root-nodule (*Rhizobium*) bacteria used to inoculate leguminous plants so they could fix atmospheric nitrogen.
- Different *Rhizobium* species infect different groups of legumes, so farmers commonly needed separate single-species inoculants.
- Prior attempts to sell mixed-species inoculants were generally ineffective because species tended to inhibit one another when combined.
- The patentee discovered that certain strains within each species do not mutually inhibit when mixed, permitting a single package containing multiple strains that remained effective.
- Kalo sued Funk Bros. Seed Co. for infringing specified product claims; Funk counterclaimed seeking a declaration that the patent was invalid.
- The district court held the product claims invalid for lack of invention and dismissed the complaint; it also dismissed the counterclaim.
- The Seventh Circuit reversed, holding the product claims valid and infringed and that the counterclaim should not have been dismissed.
- The Supreme Court granted review limited to the validity of the product claims.

## Issues

1. Whether product claims covering a mixture of naturally occurring bacterial strains selected for noninhibitive compatibility constitute patentable invention or merely claim a natural phenomenon.
2. Whether the claimed mixture qualifies as a patentable composition of matter when the combined strains perform no function different from their separate, natural functions.

## Decision

- The Supreme Court reversed the Seventh Circuit and held the challenged product claims invalid.
- The Court ruled that discovering the natural fact that certain strains can be mixed without mutual inhibition is not patentable.
- The claimed product was treated as an aggregation of natural organisms whose combined performance was only the sum of their separate performances, without a new function created by the combination.
- A concurrence agreed in the judgment, emphasizing that the claims as drafted sought control over a natural quality rather than a distinct inventive application.
- A dissent would have upheld the claims, viewing the selection and combination as producing a new and useful product.

## Legal Principles

- Laws of nature, natural phenomena, and the natural qualities of materials are not patentable and are free for public use.
- A patent cannot be sustained when the claimed advance is the discovery of a natural relationship and the remaining steps are routine implementation within the existing art.
- A composition claim requires more than assembling natural components; the combination must yield a new or different function beyond the separate natural functions of the components.
- Commercial usefulness or convenience from packaging multiple natural components together does not, by itself, supply the required inventive contribution.

## Conclusion

The Court invalidated the patent’s product claims because they effectively monopolized a natural phenomenon—the noninhibitive compatibility of certain bacterial strains—without adding a patent-eligible inventive application or creating a mixture with a function different from the bacteria’s natural, separate roles.


Funk Bros. Seed Co. v. Kalo Inoculant Co., 333 U.S. 127 (1948)