The assembly produced the so-called Paulskirche Constitution () which proclaimed a German Empire based on the principles of parliamentary democracy. This constitution fulfilled the main demands of the liberal and nationalist movements of the Vormärz and provided a foundation of human rights. The parliament also proposed a constitutional monarchy headed by a hereditary emperor ("Kaiser"). The Prussian king Friedrich Wilhelm IV did not accept the office of emperor when it was offered to him. He argued such an offer was an offence against the rights of the princes of the individual German states. In the 20th century, however, major elements of the Frankfurt constitution became models for the Weimar Constitution of 1919 and the Basic Law for the Federal Republic of Germany of 1949.