Hans Kelsen(1881-1973), was a law professor and a jurist at the Austrian Constitutional Court. He began his studies at the University of Vienna, where he completed a doctorate in law in 1906. In 1911 he began teaching law at the University of Vienna and in 1919 he became full professor of public and administrative law at the University of Vienna.
At the request of the Austrian Prime Minister at the time, Karl Renner, Kelsen drafted a new constitution for Austria that was enacted in 1920.
In the early 1930s, Kelsen received an offer to teach at the University of Cologne, but when the Nazis came to power, he was expelled from the university. He moved to Switzerland and after the outbreak of World War II he immigrated to the United States, where he taught at the University of Berkeley in California. Today, Kelsen is considered one of the greatest jurists of the twentieth century and a great influence on legal and political thought.