This article presents a comprehensive theoretical and practical analysis of the institution of necessary defense in the criminal law of the Russian Federation as a principal mechanism for safeguarding an individual's constitutional right to the protection of life, health, and other legally protected interests. The authors examine the legal nature of necessary defense, the conditions governing its lawfulness, and the distinguishing features between lawful infliction of harm and exceeding the limits of necessary defense. Particular attention is paid to the evaluative nature of the criterion requiring that defensive actions correspond to the nature and degree of the public danger posed by the attack, as well as to the challenges encountered in law enforcement when classifying the actions of a person acting in defense. Based on the analysis of judicial practice, the authors identify common errors in the retrospective assessment of actions of a person acting in necessary defense and examine their role in fostering a conviction-oriented approach. The article argues for the need to improve the explanations set forth in Resolution of the Plenum of the Supreme Court of the Russian Federation No. 19 dated September 27, 2012, particularly with respect to clarifying the criteria for proportionality in necessary defense and establishing illustrative examples of lawful defensive conduct, with a view to ensuring consistency in judicial practice in this area.