Consolidated Electric Light Co. v. McKeesport Light Co. (The Incandescent Lamp Patent Case)

Sawyer and Man obtained a patent for an electric incandescent light, which was a lighting system involving the passage of an electric current through a suitable conductor. Claims 1 and 2 of the patent described an incandescing conductor composed of “carbonized fibrous or textile material,” and Claim 3 provided that Sawyer and Man used carbonized paper as the conductor. Consolidated Electric Light Company (Consolidated) (plaintiff) filed a bill in equity against McKeesport Light Company (McKeesport) (defendant), seeking damages for patent infringement based on a lighting system developed by Edison Electric Light Company (Edison). Edison’s commercial incandescent light was designed similarly to Sawyer and Man’s, but used a conductor formed from carbonized bamboo. Edison had tested numerous categories of vegetable growth for several months before he discovered that bamboo’s parallel fibers made it a particularly good conductor. Consolidated argued that Edison’s bamboo conductor infringed the Sawyer and Man patent because bamboo was a “fibrous or textile material” covered by the patent. The circuit court considered the argument that the patent was invalid on its face because Sawyer and Man improperly attempted to claim a monopoly on all fibrous and textile materials for the purpose of electric lighting. The court held the patent invalid, and Consolidated appealed.