The subject of the article is the matter of the 'European commitment' of the Polish Senate. This question should be looked into from at least several points of view. The first tier - 'competency' concerns delimitation of the rights of the Executive and the Legislative branch with regard to the matters referring to the European Union. It is contained in the recognition that the competencies of the parliament in the widely understood 'European relations' are limited 'ab initio' while the second chamber or even wider - the parliament, is brought down to the role of a councelling, advisory body, where the Executive is the leading body. The second tier is a much wider matter having a global value. Namely, the perception of national parliaments by the European Union - conventionally referred to as 'union matter' or 'European matter' - is both undertaken and regulated, even though rather generally, by the European Union. It boils down to the indication of a general role of the national parliaments in the sphere of their European contacts, which on the one hand includes the area 'ad intra' – the internal area, whose core is the relationship of the national parliament with respective national executive bodies. The third tier can briefly and not very precisely be referred to as 'doctrinal' or alternatively 'functional'. It mainly is about an answer to the question what function/ functions national parliaments actually have. Therefore, is this function/ functions, i.e. supervisory and legislative, with the assumption of a necessary transposition in this respect which is imposed by their 'Europeisation'. Or perhaps the function associated with the European participation of national parliaments does not fit in any of the insofar existing or classic or even standard functions of the legislative branch, adopting the form of a separate and independent function - function 'sui generis'. The fourth tier - mutual relations which take place with a divided parliament, the parliament with a complex, two-chamber internal structure (conventionally referred 'structural' or 'bicameral'). The fifth tier - intranational constitutional regulations which should at least to a certain extent by consistent with the general adjudications dictated by the decisions executed at the previous tiers, namely the 'competency', the 'union', 'functional' and eventually the 'structural' tier.