Legal presumption that can be rebutted or challenged by evidence to the contrary (e.g. the presumption of liability of the custodian of a property or the presumption that a undived co-owner absent at a meeting of co-owners consents to the other co-owners representing him, if he has not, in writing, mandated a third person for that purpose or has indicated his refusal to be represented.). Its antonym is irrebuttable presumption.