He attended the Gymnasium Philippinum from 1911 to 1919, where he received an elite German secondary education focusing on classical languages and literature (at his American naturalization proceeding, he described his religion as "Homer").

Both brothers lived and studied in America on and off immediately after World War I, but Carl elected to remain in the United States and Otto to return to Germany.

They temporarily broke off relations during the 1940s because of Otto's allegiance to the Nazi party and prominent role in German industry during the Third Reich, but they reestablished contact after the end of World War II.

He stressed the necessity for maintaining the rule of law, supplemented by a strong infrastructure of civil institutions, and was highly suspicious of popular grass-roots movements.

In the 1930s, Professor Friedrich also played a leading role, with one of his students, the then-unknown David Riesman, by his side, in efforts to help Jewish scholars, lawyers, and journalists who were fleeing Nazi Germany and other Fascist regimes resettle in the United States.

He persuaded one of them, the pianist Rudolf Serkin, to give a concert at his farm in Brattleboro, Vermont, an event which led to the establishment of the Marlboro Music Festival.

[citation needed] Friedrich, who was arguably the most knowledgeable scholar in his field (of German Constitutional history) of his time, was endowed with a healthy self-regard.

[5] When the United States entered World War II Friedrich helped found the School of Overseas Administration to train officers in military government work.

[7] Friedrich traveled to Allied-occupied Germany and helped to draft the constitutions of the German federal states Bavaria, Baden, and Hesse.

[8] Friedrich's constitutional vision for a new German identity was based on active participation in democratic institutions, where citizens invested in democracy to secure their own liberty.

[11] These rapid developments prompted Friedrich to orchestrate the Human Relations Area Files (HRAF) project, which was started in 1948 by Clellan S. Ford at Yale University.

The HRAF collected and analyzed vast quantities of data to produce research reports for US diplomats on the world's cultures and political regimes.

[13] In the 1950s Friedrich had the opportunity to put his ideas of a virtuous federalism again into practice when he acted as constitutional advisor for Puerto Rico, the Virgin Islands, and Israel.

Some of the assumptions of Friedrich's theory of totalitarianism, particularly his acceptance of Carl Schmitt's idea of the "constitutional state", are viewed as potentially anti-democratic by Hans J. Lietzmann.