Acting upon the motion of the President of the Republic, the Constitutional Court of Hungary ruled in its Decision No. 13/2018. (IX. 4.) AB that the regulation which would have allowed establishing new wells up to the depth of 80m without a license or notification was contrary to the Fundamental Law. The Constitutional Court found in its decision that the regulation would endanger the volume and quality of underground water in a way that, considering the precautionary principle, was no longer compatible with the protection of natural resources and cultural artefacts forming the common heritage of the nation as laid down in Article P(1) of the Fundamental Law or Article XXI(1) of the same on the right to a healthy environment. It was in this decision that the Constitutional Court first outlined in detail the constitutional significance of the precautionary principle, with this principle forming the central part of the decision’s reasoning. Within the framework of this study I examine whether this decision based on the precautionary principle can be considered the ‘extraction’ of what is inherently present in the Fundamental Law or on the contrary, whether it was an activist approach imposing the principle on the Fundamental Law.