Informed consent is one of the key principles in safeguarding human rights in the sphere of healthcare. It presupposes the expression of the patient's free will relating to his medical examinations, treatment and diagnostic procedures, as well as the physician's duty to inform the patient on the forthcoming medical interventions, including the facts regarding the potential risks of these medical interventions. This principle is one of the elements of contemporary medical law, which has marked the transfer from paternalistic medicine to a modern model of medicine, where the patient is an active participant in the process of medical treatment. In this paper, the authors illustrate the legal aspects of safeguarding the patient's right to informed consent in the legislation and legal practices of Ukraine and the Republic of Latvia. The institute of informed consent, which needs to be safeguarded, as a key element of the legitimacy of a medical intervention (such as surgery, or vaccination), requires a specific form of fulfillment, which is conducted in writing. A medical intervention, excluding cases of emergency, is legitimate only when the consent of the patient is provided; unconsented medical interventions frequently cause lawsuits, where plaintiffs seek to recover damages for performance of a medical intervention without their informed consent. The authors have highlighted these issues while commenting on the recent case law of the Supreme Court of Ukraine and the Supreme Court of the Republic of Latvia.