Before making a decision on criminalizing a deed, which entails more serious negative consequences for a person than other violations, the increased harmfulness of the deed in question must be considered. However, criminal liability, due to its intractable repressive impact and cost capacity, is justifiable only if the ultima ratio principle is observed, namely, if the undesirable deed cannot be prevented by alternative means with equal efficiency. The article explains the origin, content, and significance of the ultima ratio principle in the modern criminal law system, which limits the legislator’s powers to criminalize. Although the role of the legislator’s political considerations in both determining the harmfulness of the deed and choosing measures to combat it cannot be eliminated, the ultima ratio principle as a specific criminal law related element of the principle of proportionality, universally recognized as a general principle of law, must be observed in formulating the corpus delicti in the Criminal Law, taking into account that the application of any criminal punishment is a restriction of human rights.