When the view of his eminence on any issue is to act as an obligatory precaution, those who follow him have a choice of either acting upon that precaution or referring to another marji’, provided that the latter is more knowledgeable than the rest of the maraji’. One can determine the level of knowledge of the maraji’ by referring to the people of expertise (known as the ahl al-khibrah) who can differentiate between mujtahids and determine the most knowledgeable.