Master/slave or M/s relationships are a special case of dominance/submission, in which the dominant has ultimate authority over the submissive. Some practitioners of M/s believe that ownership of slaves is based on an inescapable emotional state, such as total power exchange (TPE). It should be noted that the owner/slave relationship is entered into on a strictly consensual basis, without the legal force of historical or modern non-consensual slavery, which is in any case forbidden by the laws of most countries.