Most of the Jews caught up in Nazi rule and the Holocaust had been religiously observant - very broadly speaking, orthodox Poles and Lithuanians rather than assimilated Germans. Jews continued to hold prayer and study meetings, and did their best to observe religious festivals, even at the risk of their lives.
Persecution was not a new experience for the Jewish people. The historical experience of suffering is woven into Jewish liturgy. From a legal perspective, how to continue complying with the commandments, or mitzvot, in the face of oppression had already been considered at least as early as Maimonides. The mitzvot are part of the essential structure of Judaism. To a non-Jew, Jewish morality can have a legalistic appearance: to carry out a mitzvah is in itself an act of worship of G-d. As a result, responsa can be rather technical documents. They resemble opinions from counsel in the secular world - they are the work of trained legal professionals, based on authoritative jurisprudential sources and dialectical reasoning.
Rabbis began to produce responsa directed at circumstances of persecution in the 1930s; and the phenomenon continued after the War, mostly because Jews who had survived the Holocaust were seeking clearance to remarry despite not having conventional evidence that their spouses were dead. While the Holocaust was in progress, a wide variety of legal difficulties were presented to rabbis, ranging from questions of life and death to more mundane matters. Is it permissible to teach the Torah to Nazi "racial experts" if forced to do so? (Yes.) Can a male Jew recite the line "who hast not made me a slave" in his daily prayers while he is being held as a forced labourer? (Yes.) Can an electric light bulb be used in place of a Shabbat candle? (Yes, as long as it is clear and not frosted.) In Kovno in Lithuania in October 1941, one Jew made a point of asking Rabbi Ephraim Oshry about the correct Hebrew linguistic form to be used in the prayer recited before martyrdom.
Most of the responsa in the book come from Ghetto environments, but observance of the Torah was continued even in the concentration and death camps. In Buchenwald, there was a black market in tefillin. In Auschwitz, illicit sukkoth were constructed. On Purim in Buchenwald, there was a special resonance to the traditional words: "Cursed be Haman, who sought to destroy me; blessed be Mordekhai, Mordekhai the Jew".
From a secular point of view, the responsa testify to the survival of legality and learning in the midst of barbarity. From a religious point of view, they testify to the survival not only of faith but also of praxis: "Their [the Jews'] one sure link with the Divine was the performance of His commandments." The results were astonishing:
With a Torah scroll in his hands, Meir Ofen, a kabbalist and hassid of the Dzikover rebbe led hundreds of Jews during their march to a mass grave reciting Psalm 33:1, "Rejoice in God, righteous ones!" The Grodziker rebbe, prior to entering the gas chamber in Treblinka, urged the Jews to accept kiddush ha-shem [martyrdom] with joy and led them in the singing of Ani Ma'amim ("I Believe").