Today, by applying various diverse criteria to a wide range of legal persons, certain types thereof can be distinguished. The classical distinction, which is based upon the fact of participating in organizational structures of legal persons, is the division into two: legal entities of foundation (non‐ profit) vs. legal entities of corporation type. In the first part of the case study contained herein, the subject of principal considerations will be the freedom of association in the perspective of legal provisions enacted in Poland. If therefore the membership accounts for a distinctive factor of corporations, a defi nite number of members constituting the corporation is equally vital for the formation and functioning of the above‐mentioned legal persons’ types. This however appears to be a way of limitation of the freedom of association. In this context the distinguished point of reference for the respective considerations in the second part of the article is the Roman law rule of tres faciunt collegium.