a jurisprudential inquiry into the authority of the ruling jurisconsult’s opinion on proving the lunar crescent sighting

islamic azad university of maymeh, young and elite research club, maymeh, iran moon is considered a natural calendar for human individuals. proving the crescent sighting is among the issues that all human beings are somehow in need of. similarly, the islamic religious law has subjected some of the important devotional acts upon proving the crescent sighting. this very fundamental function of the moon in the matters pertaining to this world and the hereafter, has given the issue of proving the crescent sighting a special status in islamic thinking. the question that the present research would deal with is whether the islamic judge has authority over proving the crescent sighting or not. in fact, do people have to refer to their supreme legal authority (marja‘ taqlīd) concerning the crescent sighting or is the sighting among the state’s duties? jurists have expressed various views on this question: a group of renowned majority of the jurists have considered as valid the judgment of the islamic judge, whether his judgment is documented by evident proof or by his own knowledge. another group maintain the invalidity of the judgment of the islamic judge and believe that his judgment is not valid whether it is documented by evident proof, by being much reported (tawātur), by having prevalence (shuyū‘), or by the judge’s own sighting and knowledge. yet, another group maintain that if the judge’s judgment is documented by evident proof, his judgment is valid and if it is documented by his own knowledge and sighting, it is not valid. to provide an answer to the above question, the present article tries to critically review and evaluate the brought up opinions and evidences of each one of them and conclude that the judgment of the ruling jurisconsult on the proof of the crescent sighting is necessary for, and even obligatory upon all people and that all people, even the legal authorities should follow it, since authority evidences of the judgment of the islamic judge would include them, too.