Hans Kelsen was an Austrian jurist, legal philosopher and political philosopher. He was the principal architect of the 1920 Austrian Constitution, which with amendments is still in operation. Due to the rise of totalitarianism in Austria, Kelsen left for Germany in 1930 but was forced out of his university post after the Nazi seizure of power in 1933 because of his Jewish ancestry. That year he left for Geneva and in 1940 he moved to the United States. In 1934, Roscoe Pound lauded Kelsen as "undoubtedly the leading jurist of the time". While in Vienna, Kelsen met Sigmund Freud and his circle, and wrote on social psychology and sociology.

Judicial review is a process under which a government's executive, legislative, or administrative actions are subject to review by the judiciary. In a judicial review, a court may invalidate laws, acts, or governmental actions that are incompatible with a higher authority. For example, an executive decision may be invalidated for being unlawful, or a statute may be invalidated for violating the terms of a constitution. Judicial review is one of the checks and balances in the separation of powers—the power of the judiciary to supervise the legislative and executive branches when the latter exceed their authority. The doctrine varies between jurisdictions, so the procedure and scope of judicial review may differ between and within countries.