De Forest Radio Company v. General Electric Company

Background

De Forest Radio Company and General Electric Company were parties in a dispute over early dates and use of radio tube technology. The Court issued an order that amends its earlier opinion by changing specific wording about the earliest date claimed for Langmuir and by adding factual detail about how De Forest amplifying audions were used in 1912. The District Court had rejected August 20, 1912 as Langmuir’s earliest date and held that Arnold anticipated Langmuir in November 1912; the Supreme Court’s amendment records and adopts that conclusion in the opinion text.

Reasoning

The immediate question was whether the opinion’s text should reflect the correct earliest dates and technical facts. The Court stated that August 20, 1912—the date Langmuir claimed—was rightly rejected by the District Court because Arnold’s November 1912 activity anticipated Langmuir. The Court therefore ordered specific substitutions in the opinion to note that rejection and to add that, by August and by November 1912, De Forest amplifying audions were in use at about 54 volts and 67.5 volts. The opinion explains that such voltages were possible because the tubes had been sufficiently exhausted of gas, which otherwise would have ionized and glowed at about 20 to 30 volts.

Real world impact

The amendment clarifies the factual record about who used the tube technology and when, which bears directly on which earlier disclosure is treated as prior in this dispute. By correcting dates and technical details in the opinion, the Court narrows uncertainty about invention timing between the parties. This order fixes the opinion’s language rather than announcing a new general legal rule.