Thomas Edison of the Edison patent to charge a more reasonable rate for the use of the Edison patent rights and lowering the price of the electric lamp. On October 8, 1883, the US patent office ruled that Edison's patent was based on the work of William E. Sawyer and was, therefore, invalid. Litigation continued for nearly six years, until October 6, 1889, when a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid. To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison's,
Heinrich Göbel of the lamps and the method of production. Witnesses of the "Goebel-Defense" said, that reproduced lamps burnt 45, 87 and 166 hours. Edison's lamps burnt at time of applying for a patent approximately 40 hours. So-called "Goebel Original Lamps" were broken in 1893. Experts of the Edison side said that they never burnt. Lewis Latimer, an employee of the "Edison Electric Light Co." and responsible to support their counsels, discredited Goebel by demonstrating that his supposed 1870s bulb (Goebel Lamp No. 4) had been built much later. Professor van der Weyde, an 80 years old physicist, said in his affidavit,