“The separation of powers doctrine is undoubtedly one of the key principles of contemporary constitutionalism. Despite this, it has not been framed into a single, homogeneous, and thus universal form. The abundance of approaches and nuances found in legal and political doctrine makes it an extremely labile and meandering concept, which can take on a variety of shapes. Its legislative articulation is by no means uniform, and thus reproducible, either. The separation of powers in constitutional law is therefore expressed in a broad array of formulas, sometimes explicitly, sometimes implicitly. In addition, it can take on a classic, almost model form, or it can be shaped in a significantly altered manner compared to what we used to call its model […]
…the dispersion of ideas about what the separation of powers is, where it originates or how to best frame and apply it in legislation and practice does not deprive the separation of powers of the nature of a timeless general notion that underlies the very concept of the division of power. After all, the impulse to formulate the assumptions for the separation of powers was in each case triggered by the desire to eliminate the vesting of unlimited or excessive power in an individual or a narrow, oligarchised group. Therefore, its essence and also the main advantage is, first of all, protection against the despotism of power, which translates into the specific benefit of consolidation of institutional guarantees of civil rights and liberties through the attribution of individual power functions to different branches of government, and then their clear separation”.
MARCIN ROMANOWSKI, Separation of Powers: Meanders of Doctrine and Legislation