The introduction of the principle unity of civil law into the Polish civil law with the entry into force of the Civil Code in 1965 did not involve ensuring internal consistency of normative acts forming the core of civil law, i.e.: the Civil Code, regulations regarding commercial companies contained in the 1934 Commercial Code, the Family and Guardianship Code, and the law on land and mortgage registers. The Code of Commercial Companies of 2000, to some extent, but not completely, pursued the postulate of ensuring the consistency of the provisions of the Civil Code and the law of commercial companies. In the legal literature, attention is paid increasingly to the necessity to complete the process of adjusting the Commercial Companies Code to the Civil Code as well as the introduction of relevant modifications and corrections to the Commercial Companies Code ensuring the necessary coherence of the legal regulations of these codes. In the first place, this is required by the following issues: Firstly, concerning the nature, manner and scope of applying the freedom of contract principle in the area of legal regulation of commercial companies. Secondly, the relation between the provisions of the Civil Code concerning acts in law, in particular contracts, and articles of association in commercial companies as well as the so called invalidity of articles of association (Article 21 CCC). Thirdly, the issues concerning the concept of an act in law and resolutions of a capital company body, invalidity of an act in law and challengeability of a resolution of the general meeting or of the general assembly of a capital company, as well as the explanation of the so called non-existent resolutions. Fourthly, the legal and financial status of the spouses where at least one of them is a participant in a commercial company. Fifthly, synchronization of the provisions of the Act on the National Court Register concerning registration procedure with structural provisions of the Commercial Companies Code concerning the functioning of commercial companies. The application of adequate provisions of the Code of Civil Procedure is to be considered in this respect.