With the legal institution of consent, criminal law provides the rights holder with a tool to manage their rights as they wish, allowing them to disclose their rights for self-determined purposes. In this way, it enables someone who interferes with a legal right to affect another's rights without fearing criminal penalties. Consent is particularly significant in medical criminal law practice concerning whether a physician performing a medically indicated treatment commits a criminal offense, or on what grounds such criminal liability could be denied. This work primarily addresses questions regarding the rationale for consent, with the substantive design of the concept of legal rights playing a central role. Building on the unique approach developed here, there will be a discussion of the doctrine of defects of will. Following this, the practical implications of the proposed solutions for medical interventions will be presented.