But there are severe differences within the fiqhs themselves. Remember, it has been hundreds of years since last of the four imams die and did their ijtehad. And these imams can not rule on new issues of today. Thus within one fiqh, there are differences about whether music is allowed, or what kind of music is allowed. Or whether picture taking is allowed, or how severe a sin it is.
So who has authority now to resolve these differences? Which version would the state follow? The “official” version of tyrant, obviously. But that version may or may not be accurate.