The Constitution forms the basis for the legal organisation of the Sejm. Art. 112 of the Constitution provides that the internal organisation and conduct of the work of the Sejm as well as the procedure of constituting its organs are specified in the rules of procedure, adopted by the Sejm. Constitutional provisions directly provide for the existence of certain of the Sejm organs. Art. 110 mentions the Marshal and the Vicemarshals of the Sejm, as well as standing and special committees. The establishment of the remaining bodies of the Sejm and their competence are regulated in the rules of procedure of the Sejm. The latter act also determines the principles and range of the activities of the Presidium of the Sejm and the Council of Seniors.

The Marshal of the Sejm performs a vital role in the structure of the Chamber of Deputies. He is elected during the first sitting of the Sejm after parliamentary elections by an absolute majority vote in the presence of at least half of the statutory number of Deputies. The Constitution attributes the Marshal with the right to preside over the debates of the Sejm; he safeguards the rights of the Chamber and acts as its representative. Additionally, the Constitution states that the Marshal heads the National Assembly, temporarily performs the duties of the President if the latter is unable to do so, and orders presidential elections; the President seeks the opinion of the Marshal of the Sejm prior to shortening the term of office of the Sejm. Both the Constitution and the rules of procedure of the Sejm acknowledge the essential rights of the Marshal as regards the legislative process. The Vicemarshals of the Sejm act as deputies of the Marshal in his parliamentary duties and responsibilities.