The article is focused on an analysis of a decision of Constitutional court of Slovak republic PL. ÚS 21/2014-96 from the viewpoint of core of constitution theory. The aim of this article is not only to describe and characterise theory of core of constitution, but to also present drawbacks of this theory. In the introduction we analyse the core of constitution and eternity clause concepts, followed by an analysis of this clause as a limitation of the power of people and constitutional body, continuing by description of the very concept of core of constitution. In the end we construct a logic argument proving that legal embodiment of constitutional core is not only legally irrational but also dangerous, because it serves as a way for legislation to avoid critique.