## Facts

- A foreign inventor obtained patents covering a process and apparatus for producing very fine lead powder used in storage batteries and filed U.S. applications on July 14, 1923 and April 27, 1926.
- Independently and without knowledge of the inventor’s work, a U.S. manufacturer installed a machine in early 1921 that practiced substantially the same process and began commercial production in June 1921.
- The manufacturer’s use occurred inside its factory in the regular course of producing lead powder for profit.
- The machine and process were not hidden and were accessible to employees and others with legitimate business in the plant.
- The patentee (through an assignee) sued for infringement; the manufacturer asserted that its pre-filing factory practice constituted “public use” for more than the statutory period, barring the patents.

## Issues

1. Whether a patent for an invention made abroad (and not patented or published abroad) is enforceable against an innocent domestic user whose use began after the actual foreign invention date but before the U.S. filing date.
2. Whether ordinary, non-experimental practice of a machine or process inside a factory to produce goods for commercial purposes constitutes “public use” under the statutory bar.
3. Whether patent statutes governing foreign filings and foreign prior knowledge/use restrict proof of the actual foreign invention date or otherwise shield the patentee from a domestic prior-use defense not covered by any patent.
4. Whether abandonment can be considered when it was not pleaded as an affirmative defense.

## Decision

- The Supreme Court reversed the judgment for the patentee and held the asserted claims invalid.
- A foreign inventor may prove the actual date of invention abroad to defeat a domestic “knowledge or use” defense where the domestic activity began after the invention date but before the U.S. filing date, and no patent right is claimed by the user.
- The statute governing foreign patents did not bar proof of the actual foreign invention date for that purpose.
- The statute excusing certain foreign prior knowledge/use based on the applicant’s belief of originality did not apply where the defense rested on unpatented domestic knowledge or use.
- Abandonment is a fact question and an affirmative defense that must be pleaded and proved; failure to plead it waived the defense.
- The manufacturer’s ordinary, for-profit factory practice of the process and machine for more than two years before the U.S. filing dates was “public use,” triggering the statutory bar and invalidating the patent claims.

## Legal Principles

- Ordinary use of a machine or practice of a process in a factory, in the usual course of producing articles for commercial purposes, constitutes “public use” even if confined to the user’s premises and not disclosed to the general public.
- Experimental use does not constitute “public use,” but routine commercial production for profit does.
- A patent is barred if the invention was in public use in the United States for more than the statutory period before the patent application was filed.
- In a dispute between a patentee of a foreign invention and an alleged infringer asserting only unpatented domestic prior use, statutory protections aimed at foreign prior knowledge/use do not negate the domestic public-use bar.
- Abandonment is an affirmative defense that must be pleaded and proved; failure to plead it results in waiver.

## Conclusion

The Court held that routine commercial factory practice of a process or machine for more than the statutory period before a patent application is filed is “public use” that invalidates the patent, and it enforced pleading requirements by treating abandonment as waived when not raised as an affirmative defense.


Electric Storage Battery Co. v. Shimadzu, 307 U.S. 5 (1939)