Reborn in 1918, the Polish state inherited from the partition countries: Russia, Prussia and Austria their legal systems. The task of unifying the codification of the law was entrusted to the Codification Commission, established on the basis of the Act of 1919. The Commission was to prepare draft legislation in the field of civil and criminal law. It was a body of 44 lawyers and had a high degree of independence from political factors. As a result of the Commission’s work, more than 20 legal acts were created. In the area of civil law, these were laws mainly related to foreign legal transactions. These included, among others, bills of exchange and cheque law, copyright law, patent law, law on combating unfair competition. The two laws of 1926 were of particular importance: private international law and inter-district law. Three codes of private law were also created: the Code of Obligations (1933, considered the most outstanding civil work of the Commission), the Commercial Code and the Code of Civil Procedure. In the area of criminal law, a full codification was carried out, first by implementing the Code of Criminal Procedure (1928) and then the Criminal Code (1932). These two acts were based on different doctrinal bases, which made criminal law inconsistent. The Criminal Code of Juliusz Makarewicz in particular was an outstanding work, based on the findings of the School of Sociological Criminal Law. The Codification Commission did not finish its work until the outbreak of the war. However, present codes are largely based on the solutions developed within the Commission.