On October 9, 1981, Judge Thomas T. Johnson of the Superior Court of Los Angeles ruled once and for all that Jews had indeed been gassed to death in Auschwitz. It was the first time a court in the United States had ruled that the existence of the Holocaust was something that did not need to be proved when it arose in a court case.
Judge Johnson’s ‘judicial notice,’ acknowledging the incontrovertibility of the fact that Jews had been gassed in Auschwitz, came in the case of survivor Mel Mermelstein. He had sued the Institute for Historical Review, a self-styled ‘revisionist’ group, when it refused to pay him the sum of $50,000, which it had promised to pay for ‘verifiable proof that gas chambers for the purpose of killing human beings existed at or in Auschwitz.
Source: Green, David B. “This day: A U.S. Court Rules That the Jews Were Gassed in Auschwitz," Haaretz, (October 9, 2015)