What does it take to remove evil and stop hatred? This question has plagued humans throughout centuries, and although there is no simple answer, Germany changed from a pariah state to exemplar of constitutional democracy through the combination of post-World War II criminal trials, reforms of law and media, and investment by new generations who asked their parents persistently, “Where were you during the war?” A crucial element came with the criminal trials, initially through the international military tribunal and then subsequent state-based prosecutions.

Seventy years ago, on Sept. 29, 1947, 27-year-old American lawyer, Ben Ferencz, gave the opening statement in a landmark international trial of Nazis conducted not only to punish perpetrators but also to help demonstrate justice to Germans and to the world. The Einsatzgruppen case pursued leaders responsible for the mass murder of approximately 1 million Soviet Jews. A group of security personnel and police under German command methodically worked to eliminate perceived enemies of the Third Reich, which meant Jews, Gypsies, communists, people with disabilities. Firing squads shot civilians until, to relieve distress by those on the ground, poison gas became the killing method of choice. This was the first trial in which prosecutors used the word “genocide.”

Remembering the Einsatzruppen case matters not just because of this contrast, and not just because of the urgent need to replenish, in the United States and in the world, commitments to law, facts, and individual rights. The case matters more than ever because the evidence showed that the perpetrators were not somehow naturally killers; they were trained and coaxed, nudged and shaped by Nazi propaganda, organizations. Groups of Germans, depressed by economic and military failures, accepted the argument that national rehabilitation would come through racial and ideological purity, and whatever legal and illegal actions needed to attain it. In coming to terms with this horror, American and international leaders sought to expose the truth: Racial and religious genocide violated the most fundamental principles of German law as well as of universal human rights

Although political pressures led to the premature release of many of those convicted, and many former Nazis went on to powerful posts, the trial contributed to the vigorous, painful efforts by Germany to face how Nazism took hold and how to prevent it from happening again. The trials created factual records and a basis for questions for new generations, asking of their elders, “What did you do during the Third Reich?” Vigorous efforts to rewrite textbooks, change training for teachers, and persist in overhauling education despite initial set-backs, changed the schools and German society over the long term.

The new constitution and the courts devised protections for speech and the press while also restricting public displays of symbols of unconstitutional organizations, and outlawing sale or distribution to minors of hateful, violent works. Now, Germany models for the world what it takes to say no to Nazism and to recognize the humanity of refugees, and all human beings

These were not steps adopted by the United States after the Civil War, after Ku Klux Klan terrorism in many regions of the United States, or after other waves of hatred and violence. We now face new white supremacist and nationalist claims, new demonization of individuals because of their national origins, religion, or race, new failures by leaders in the highest places to be firm in condemnation and commitment to bring change. Ben Ferencz, the young lawyer who opened the Einsatzgruppen case, is now 97, still crusading for law, peace, and the cessation of state-sanctioned hatred. Now, 70 years later, shouldn’t the United States learn from Germany about what we, too, need to do?

Martha Minow is professor of general jurisprudence at Harvard Law School and Harvard University distinguished service professor. Published on Tikkun’s website by permission of the author.