De Zayas has written and lectured extensively on human rights, including the jurisprudence of the United Nations Human Rights Committee, the Armenian Genocide, the US-run detention centers at Guantanamo Bay "ethnic cleansing" in the former Yugoslavia , the expulsion of Eastern European Germans after the Second World War , the invasion of Cyprus by Turkey in 1974 , the rights of minorities, and indigenous peoples.. He is an advocate of "the right to homeland" as a universal human right.
While de Zayas' literary output and his international law and human rights publications are mainstream, his peace activism has rendered him somewhat controversial . Since his retirement from the UN in 2003, de Zayas has become a vocal critic of the Iraq war , indefinite detention in Guantanamo, secret CIA prisons, nuclear pollution, and extreme poverty. He has chastised the United States, Great Britain, and Germany for their lack of intellectual honesty and their lip service to human rights. St. Galler Tagblatt 14 May 2004 "Verbrechen gegen den Frieden bestrafen"
De Zayas' family is of Spanish and French descent. He grew up in Chicago. He earned his juris doctor from Harvard Law School and a doctorate of philosophy in modern history from the Georg-August University of Göttingen. He practiced corporate law in New York and family law in Florida, as member of the New York and Florida Bars. He was also a Fulbright Fellow at the University of Tübingen and research fellow at the Max Planck Institute for Comparative Public Law and International Law in Heidelberg. In 1978-80, he participated in the German-American Schoolbook Commission at the Georg Eckert Institut in Braunschweig and in 1980 published a long article on the subject of prejudice and stereotypes in schoolbooks in "Aus Politik und Zeitgeschichte"..
During the course of his legal and academic career, he has been a visiting professor of international law and of world history at a number of institutions, including the Graduate Institute of International Studies (Geneva), the DePaul University College of Law (Chicago), the University of British Columbia (Vancouver), the Geneva School of Diplomacy and International Relations, the Schiller International University (Leysin), the Académie Internationale de Droit Constitutionnel (Tunis), the University of Trier, the Santa Clara Law School, the Center for Applied Studies in International Negotiations (CASIN, Genève), the Institut de Droits de l'Homme Strasbourg, the Felix Ermacora Institute in Vienna, the Raoul Wallenberg Institute in Lund (Sweden), and the Universidad de Alcalá de Henares (Madrid). He has been member of doctoral commissions at Institut Universitaire de Hautes Etudes Internationales, the universities of Amsterdam, Alcalá de Henares (Madrid), and the Geneva School of Diplomacy.
De Zayas regularly publishes op-ed articles and essays in German and Swiss newspapers, including the Frankfurter Allgemeine Zeitung, Die Welt, Das Parlament, Der Spiegel, Bayernkurier, Zeit Fragen, and the Tribune de Genève. He has made television appearances on round tables and panels for CNN, WDR, WDR's Monitor, WDR's "Alte und neue Heimat", Phoenix, 3sat, ZDF, ZDF-Magazin, Südwestfunk/Baden-Baden, "Report", Aschaffenburger Gespräche, Bayerischer Rundfunk, Léman Bleu (Geneva) etc. He has been legal and historical consultant to numerous television documentaries in the US, Canada, the Netherlands and Germany, including the Discovery Channel film on the sinking of the refugee ship "Wilhelm Gustloff", and the Bayerischer Rundfunk documentary "Flucht und Vertreibung". He regularly gives radio interviews to Deutschlandfunk, Deutsche Welle, Radio Cité (Geneva), WBAI (New York), and other stations.
De Zayas is a Roman Catholic and resides with his Dutch wife in Geneva.
According to press articles, he has been a registered Republican in the United States since 1968, when he was a Harvard student and active member of the Harvard Republicans, but has voted for the Democratic party since 2004.
While de Zayas' human rights publications largely reflect United Nations positions, his historical research and conclusions regarding the transfer of ethnic Germans from Eastern Europe at the end of WWII, a topic that had been hitherto largely neglected by academics, have given rise to much controversy . In 1975, he published a study in the Harvard International Law Journal in which he questioned the legality of the expulsion of possibly as many as 15 million Germans from their homes after World War II, invoking the Atlantic Charter, the Hague Conventions, and the Nuremberg Principles. The article was followed by the book Nemesis at Potsdam which focused on the degree of responsibility of the Anglo-Americans for decisions leading to the expulsions of these ethnic Germans. U.S. Ambassador and Eisenhower advisor Robert Murphy wrote the preface. In the same year, an enlarged German edition was published by the foremost legal publisher in Germany, C.H. Beck, becoming a bestseller, and was quickly reissued by Germany's largest pocketbook publisher, Deutscher Taschenbuch Verlag. In this book, de Zayas took an interdisciplinary approach to the phenomenon of population transfers and examined the situation of the ethnic Germans from both an historical and legal perspective. De Zayas was the first American historian to address this topic. . As law professor at DePaul in Chicago, he organized an exhibit entitled "Ethnic Cleansing 1944-1948", which ran from November 1993 to February 1994, consisting of more than 100 poster-sized Wochenschau, Bundesarchiv and US-Army Signal Corps pictures, as well as paintings by survivors of the expulsion, which was widely visited and commented in the Chicago press.
His second book, The Wehrmacht War Crimes Bureau was published in Germany by Universitas/Langen Müller. Professor Howard Levie, a noted expert in international humanitarian law, wrote the preface. This book describes some of the work of the Wehrmacht-Untersuchungsstelle, a special section of the legal department of the Oberkommando der Wehrmacht, which investigated Allied and German war crimes. Examples include the murder of Ukrainians in Lviv by the NKVD in 1941, the murder of Polish prisoners of war at Katyn in 1940, executions of German PoWs by French irregulars in 1944, and the sinking of the German hospital ship "Tübingen" by the British in 1944. De Zayas was the first researcher to see and evaluate the extant 226 volumes (only about half of the total records, the rest apparently having been burned in Langensalza, Germany near the end of the war, according to de Zayas.), which had been classified documents in the United States and had just been returned by the US National Archives to the German Bundesarchiv. The book was savagely attacked in the media of the Soviet Union and its satellites. Notwithstanding criticism from a few historians in Germany, Nemesis at Potsdam and The Wehrmacht War Crimes Bureau were well-received in the academic community, are used in colleges and universities, and remain in print thirty years after their initial publication, in the 14th and 7th revised and updated editions, respectively.
De Zayas was co-President with Jacqueline Berenstein Wavre of the Association Suisses et Internationaux de Genève (1996-2006). ASIG was particularly active in the cultural integration of international civil servants into Geneva life, an activity currently carried out by the "Geneva Welcome Centre" at the Villa la Pastorale in Geneva. It also organized numerous round tables at the United Nations and other public events with a view to promoting Switzerland's entry into the United Nations. On 11 November 1998 ASIG hosted a conference at the Palais des Nations on "Denis de Rougement ou l'art de penser en avant les problèmes". On 12 May 1999 ASIG hosted a conference by Professor Peter Tschopp, Director of the Institut Universitaire de Hautes Etudes Internationales, on "La Suisse et l'ONU" at the Centre d'Accueil Genève Inernationale. ASIG also hosted round tables at the Office of the UN High Commissioner for Human Rights at the Palais Wilson 2000-2002
He is currently treasurer of Millennium Solidarity, a Geneva non-governmental organization working for world peace and the eradication of poverty . He has participated on podium discussions at the UN and chaired an expert panel on peace, disarmament and powerty at the Civil Society Development Forum on 28 June 2007 in Geneva. Millennium Solidarity has synergies with the Geneva Institute for Peace , CETIM -Centre Europe- Tier Monde
He is a member of the Asociación Española para el Desarrollo del Derecho Internacional de los Derechos Humanos (AEDIDH), which in October 2006 produced the "Luarca Declaration on the Human Right to Peace" . He has represented AEDIDH, the International P.E.N., and the International Society for Human Rights at round tables at the United Nations in Geneva. , including with Special Rapporteur on the Right to Food, Professor Jean Ziegler, and with the Chairman of the Human Rights Council, Ambassador Luis de Alba. He is an advocate of the human right to peace and a signatory of the "Luarca Declaration on the Human Right to Peace"
While at the U.N., de Zayas was the founder and editor of the series "Selected Decisions of the Human Rights Committee under the Optional Protocol." He is a regular participant in panels and round tables at the United Nations, where he represents the International Society for Human Rights. During the 4th, 5th, 6th and 7th sessions of the Human Rights Council, he participated in panels on various issues including the right to development, extreme poverty, the millennium development goals, moderated a panel on human dignity, and presented the statement of Secretary General Ban Ki Moon on the International Day of Human Rights, 21 September 2007.
De Zayas has published poetry in English, French, German, Spanish, and Dutch, translated Rainer Maria Rilke into English, French, and Spanish, translated Joseph von Eichendorff and Hermann Hesse into English. .
As a member of the International Rainer Maria Rilke Society (Sierre, Switzerland), he published the first English-language translation of Rilke's "Larenopfer", 90 poems dedicated to Rilke's homeland of Bohemia, and hometown of Prague (with a historical commentary, Red Hen Press, Los Angeles, 2005). With this book, de Zayas opened a new facet of Rilke research: Rilke as Heimatdichter or poet of the homeland, poète du terroir - spanning Rilke's early poetry characterized by enthusiasm for the beauties and the history of his homeland through Rilke's final poetic testament -- more than 400 poems in French, dedicated to the Valais in Switzerland (Quatrains Valaisains, Roses, Fenetres, Vergers), Rilke's "Wahlheimat", where he spent the last years of his life at the Château de Muzot in Sierre and where he is buried in nearby Raron. Hitherto, Rilke had been understood primarily as a metaphyscial poet, as a poet's poet, but never seen as a homeland poet. Zayas has lectured and published on Rilke's search for a sense of belonging and his grateful attachment to a landscape and to the real people who live there.
He has also published in the literary journal of the PEN Club Suisse romande "L'Escarpe". A member of International PEN since 1989, he was secretary of the Swiss-French PEN in 2002-06, and is currently its president. De Zayas has been President of the PEN Club in the French-speaking cantons of Switzerland since 2006.
De Zayas served for 15 years as president of the United Nations Society of Writers (Geneva). De Zayas was the founder of the UN literary review Ex Tempore ISSN 1020-6604, which has published 18 issues . . In May 2007 he was reelected editor-in-chief of Ex Tempore.