Although the earlier Imam (a.s .) too practiced this “Law of Exception” yet its use has been more widespread in the period of major occultation. Imam Sadiq (a.s .) has urged his followers to consult those scholars who are well versed in the permitted (Halal) and the prohibited (Haram) things. As he (a.s .) put it:
Yeye alikuwa naibu wa Imamu Ali Naqi (a.s.) na Imamu Hassan Askari (a.s.) na vile vile aliishikilia kazi hiyo wakati wa Imamu Mahdi (Amani ya Mwenyezi Mungu iwe juu yao wote) na baada ya kuifanya kazi hiyo kwa miaka kadhaa, alifariki mjini Baghdad (Iraq) ambako alizikwa.