The main task of this book is to deliver an in-depth analysis of the idea of the state in the reflection of Robert von Mohl (1799-1875). This German liberal scholar and politician developed comprehensive theory of the state, which combined both absolutist and liberal trendencies. In the book, Von Mohl's political philosophy is depicted against the backdrop of the sociopolitical situation of German states in the nineteenth century.The main focus of the book is one of von Mohl's most important intelectual achievements, namely - the concept of Rechstaat. In conclusion, the author draws similarities between various von Mohl's ideas and the situation of contemporary legal institutions in Germany and Poland.