Consent (BDSM)
Consent within BDSM is when a participant gives their permission for certain acts or types of relationships. It bears much in common with the concept of informed consent. It is an issue that attracts much attention within BDSM, as well from outside observers.
Legal consent is a separate and largely unrelated matter. The importance of consent is simultaneously a personal, ethical, and social issue. Acts undertaken with a lack of consent are considered abusive and shunned within the BDSM subculture.
Concept
Consent is an explicit agreement to acts, terms, and conditions. It can be confirmed verbally and/or in writing.
The underlying principle is a classical liberal idea that a person's freedom can be measured by lack of interference with their personal choices. As in classical liberalism, the harm principle comes into play. Consent, within BDSM and some academic schools of thought, is what separates legally actionable harm from legitimate personal freedom.
Informed consent is the idea that consent is offered with sufficient information and understanding of what is being agreed upon. As in vanilla society, an impairment of mental state or decision making abilities is considered a state in which informed, rational consent cannot be offered.