The issue of “sanctions” applied by States and some international organizations (mainly the EU), which are not directly injured entities, is one of the most complex issues in the theory and practice of contemporary international law, not only because of their frequency and scope in the last two decades. It came into the spotlight again because of the very extensive and gradually supplemented restrictive measures taken by the EU against Russia, firstly after the annexation of Crimea in 2014, but mainly in response to the aggression against Ukraine from February 2022. These restrictive measures, often also called “sanctions”, represent an extensive set of measures, with additions and exceptions, which have different content, but also different legal nature. These are diplomatic measures, restrictions of an economic and financial nature, traffic restrictions, both general sanctions (against the State) and measures targeted at individual state organs and private individuals who are considered connected to the Russian government and supporting its aggressive policy. The measures in question are not Security Council sanctions under Chapter VII. of UN Charter, but the unilateral measures of some States and the EU. Therefore, the legality of such measures must be assessed from the point of view of international law. Some of the measures have their content that is not intrinsically unlawful (retorsions), or have legal basis in treaty-based exceptions and clauses on essential security interests. For others, we can find their justification based on the rules of general international law, as a countermeasure. This institute is the modern equivalent of traditional peaceful reprisals, the current regulation of which can be found in the articles on State responsibility (ARSIWA) adopted by the International Law Commission. Therefore, it is necessary to respect the substantive and procedural conditions of the legality of countermeasures contained therein.