The article offers a philosophical and legal substantiation of mental integrity as a constitutional value amid the rapid development of neurotechnologies capable of reading, recording, and influencing human brain activity. The relevance of the topic stems from the fact that traditional constitutional doctrine has historically protected bodily integrity far more consistently than the integrity of a person’s mental sphere, whereas contemporary neurodevices, such as portable electroencephalographic headsets and brain-computer interfaces, are already capable of accessing information about a person’s internal mental processes without verbal mediation. The author proceeds from the premise that the right to mental integrity requires an independent philosophical foundation that cannot be reduced mechanically to already established constitutional categories such as privacy or bodily autonomy. The article analyzes the classical philosophical problem of mind-body dualism and its influence on the asymmetrical legal protection historically afforded to these two spheres of personality. Contemporary philosophical approaches to justifying the right to mental integrity are examined, including an intuitive-abductive line of argument and an approach that derives this right from the value of autonomous decision-making. The article further explores the multidisciplinary doctrine of «neurorights,» which distinguishes mental privacy, mental integrity, and cognitive liberty as distinct, though interrelated, categories of protection. It analyzes the first ruling of its kind in global judicial practice – the 2023 judgment of the Supreme Court of Chile concerning the protection of a consumer’s brain data collected by a neurotechnology device, which found the commercialization of neurodata to violate the constitutional right to mental integrity. It is concluded that mental health and mental integrity should be treated as an independent constitutional value requiring dedicated, specialized mechanisms of legal protection that go beyond existing regulation of bodily autonomy and personal data protection. The article proposes a set of criteria for distinguishing lawful from unlawful interference with a person’s mental sphere in the context of neurotechnology deployment.