Belle Mayer trained as a lawyer and worked for the General Counsel of the US Treasury, Foreign Funds Control Bureau. This bureau worked to enforce the Trading With the Enemy Act passed by Congress. In this capacity, Mayer became familiar with the German I. G. Farben chemical company, a large conglomerate that used slave labor during World War II. In 1945, Mayer was sent as a Department of Treasury representative to the postwar London Conference. She was present as representatives from the Allied nations outlined the principles of law for the prosecution and trial of Europe's major war criminals. Mayer reported to this commission as it prepared for upcoming war crimes trials. She was then among the attorneys (including her future husband William Zeck) who prepared the indictment against the I. G. Farben company at the Nuremberg trials.
It's interesting how much every citizen in not only the United States, in the world, from the youngest to the oldest, from the religious to the non-religious, prattle about peace and so few of us try to do anything concrete about it. You have people like Benjamin Ferencz and like Henry King of Ohio, who have since the Nuremberg trials, dedicated their entire, have spent this past 50 years dedicated to the strengthening of international law, to the perpetuation of the Nuremberg principles and to the cause of human rights.