## Facts

- Automatic Devices Corp. owned Mead patent No. 1,736,544 (filed 1927; issued 1929) covering an improvement to cordless automobile cigar/cigarette lighters.
- Earlier automobile lighters included cable “reel-type” designs and later “wireless/cordless” lighters that heated while seated in a socket.
- In the prior cordless designs, the user had to keep a plug/button depressed until the heating element reached lighting temperature.
- Mead’s device combined an existing cordless lighter configuration with a thermostatic control that opened the circuit when the coil reached the proper temperature, returning the plug from “on” to “off” automatically.
- Thermostatic controls that opened or closed electrical circuits at a given temperature were already known and used in other electrical appliances.
- Automatic Devices sued Cuno Engineering in equity for infringement, asserting (among others) claims 2, 3, and 11.
- The district court found no infringement; the Second Circuit reversed and held the claims valid and infringed.
- The Supreme Court granted certiorari limited to whether claims 2, 3, and 11 were valid.

## Issues

1. Whether adding a known thermostatic control to an existing cordless automobile lighter to produce automatic shutoff constituted patentable invention, or merely an application of ordinary mechanical skill.

## Decision

- The Supreme Court reversed the Second Circuit.
- Claims 2, 3, and 11 were held invalid for lack of patentable invention.
- Because the asserted claims were invalid, the infringement judgment could not stand.

## Legal Principles

- A patentable advance requires more than the routine skill of an ordinary mechanic in the relevant art; usefulness alone does not establish patentability.
- A combination of old elements is not patentable when it yields only a predictable result indicated by the prior art.
- Applying a well-known control or mechanism to an analogous device, where the art suggests the application and the result is expected, lacks the requisite inventive quality.

## Conclusion

The Court held that Mead’s automatic-shutoff lighter did not amount to patentable invention because it merely applied a known thermostatic circuit-opening control to an existing cordless lighter design to achieve a foreseeable improvement in convenience.


Cuno Eng'g Corp. v. Automatic Devices Corp., 314 U.S. 84 (1941)