This diploma thesis deals with the natural law and six of the most important Austrian representatives.First, the natural law is described as a mind-set and as a historical age.In the second part of the thesis the representatives, Joseph Azzoni, Johann Horten, Mathias Haan, Karl Anton Martini, Franz Zeiller and Paul Riegger, their lives, work and excellent performance are described. Most of them were not only scientists but also practitioners.The thesis here takes a closer look at Azzoni, Martini, Zeiller and Riegger, who kept busy to make the law studies better by reforming it as they were members of the study committees. Moreover Riegger, Martini and Zeiller made excellent work in the field of established ecclesiastical law. They accounted for the abolishment of the churchs influence on the state. For this reason Rieggers "Institutiones iurisprudentiae ecclesiasticae" is described in detail. Another part treats Haan?s and Zeiller?s brilliant work in the field of criminal law. They composed criminal and criminal procedure codes. The diploma thesis also deals with Haan?s excellent work and his expertise about the general court rules.The age?s most important result, the ABGB?s historical origin is also described. 1753 Azzoni started with his master plan the codification works, which is a rough arrangement of the Codex Theresianus. Horten revised this Codex. That was the reason why the parentela system was introduced in the ABGB. Martini reworked Hortens concept completely. Martini performed extremely well with the legal norms of compensation of damage and agreement. Martinis concept was enacted in Galicia. Finally, Zeiller completed the ABGB?s work. He was entrusted to rephrase the norms perfectly. Only because of these brilliant representatives the ABGB could be enacted in 1811.