## Facts

- In 1874, Joseph F. Glidden obtained U.S. Patent No. 157,124 for an “Improvement in Wire Fences,” addressing problems with earlier barbed-wire fences whose barbs could slip or require hammering to secure them.
- Glidden did not claim to have invented barbed wire as a general idea; barbed-wire fences were already known. His claim focused on a specific construction that held barbs in place more reliably.
- The claimed design used twisted fence wires with a short transverse “spur-wire” (barb) bent at its middle around one strand of the twisted wire; the other strand, by twisting around its mate, clamped the spur-wire and held the projecting ends in position.
- The practical effect of the design was that the barbs could be secured by the twisting structure itself rather than by separate fastening or repeated hammering, making the product workable and widely marketable.
- Washburn & Moen Manufacturing Company acquired Glidden’s patent rights and filed a bill in equity in federal circuit court against competing barbed-wire producers and fence sellers (including the Beat ’Em All Barbed-Wire Company and others), alleging infringement.
- The defendants challenged validity, arguing the claimed improvement lacked novelty because similar barbed-wire structures appeared in earlier patents or were already in use when Glidden applied.
- A significant part of the defendants’ anticipation case rested on alleged prior, unpatented devices and supposed earlier uses described mainly through witness recollections.
- The Circuit Court for the Northern District of Iowa held the patent invalid for want of novelty and ruled for the defendants.
- Washburn & Moen appealed to the U.S. Supreme Court.

## Issues

1. Whether Glidden’s barbed-wire improvement—securing barbs in place through the twisted-wire construction without hammering—was sufficiently novel to be patentable despite earlier barbed-wire designs and claims of prior use.

## Decision

- The Supreme Court reversed the circuit court’s decree and held Glidden’s Patent No. 157,124 valid (and enforceable against the defendants).
- The Court concluded that Glidden’s claimed arrangement constituted an inventive advance over what had come before, even though the general category of barbed wire was known.
- The Court held that when a party asserts an unpatented device as a complete anticipation and proves it only by oral testimony, the proof must be “clear, satisfactory and beyond a reasonable doubt.”
- Applying that demanding standard, the Court found the defendants’ oral-evidence showing of prior unpatented anticipation inadequate.

## Legal Principles

- An improvement can be patentable even if the broader product type is already known, so long as the improvement itself is new and useful and is not anticipated by prior art or prior public use.
- Courts may sustain a patent for the step that turns repeated earlier attempts into a working, successful construction, when that step reflects invention rather than routine skill.
- A defense of anticipation based on alleged prior, unpatented devices shown only through oral testimony requires unusually strong proof: it must be clear, satisfactory, and beyond a reasonable doubt.
- Evidence of wide adoption and market acceptance may support a finding that an asserted improvement reflects invention, especially when the record shows others tried and failed to achieve the same practical result.

## Conclusion

Washburn & Moen Manufacturing Co. v. [Fence Sellers] held that Glidden’s specific barbed-wire improvement—using a twisted-wire structure to clamp and hold barbs without hammering—was a patentable advance over prior designs, and it set a demanding proof requirement for anticipation defenses that rely on oral testimony about alleged unpatented prior devices.


Washburn & Moen Manufacturing Co. v. [Fence Sellers], 143 U.S. 275 (1892)