Buren of proof (Latin, onus probandi) is the obligation to prove allegations which are presented in a legal action. Under the Latin maxim necessitas probandi incumbit ei qui agit, the ordinary rule is that "the necessity of proof lies with he who complains." For example, a person has to prove that someone is guilty (in a criminal case) or liable (in a civil case) depending on the allegations; a person is not required to prove his or her own innocence, it is rebuttably presumed. More colloquially, burden of proof refers to an obligation in a particular context to defend a position against a prima facie other position.