It must be known that ijtihad has different elements: some are firm (ex. Quran, prophetic traditions, intellect…) and others are changeable (ex. Subjects and their conditions, knowledge and the understanding of the marja himself). A mujtahid must always be aware of the changeable elements. Hence, it is possible for the verdict of one mujtahid to change over time. According to a general principle, if the verdict of a marja changes one is unable to act according to the previous verdict, rather he must act according to the new verdict. If a marja dies we do not know if his verdict would remain the same after his death when realities are shown to him, because after death all of the correct answers to religious problems would become clear for him. Before death he derived the verdict from the books, but after his death there are no more books, schools, or seminaries, rather the truth will be made clear for him.
With all of this, it is not the case that a marja’s verdict becomes invalid after his death, rather the opinion of most jurists is that those who performed taqlid to that marja are able to remain on his taqlid with the permission of a living marja. Some high scholars also claimed that it is permissible to perform taqlid to the most knowledgeable dead marja from the start.
Ijtihad has different elements: some are firm (ex. Quran, prophetic traditions, intellect…) and others are changeable (ex. Subjects and their conditions, knowledge and the understanding of the marja himself). Since a mujtahid is responsible for the verdicts he makes and must answer to Allah regarding them, he must always pay attention to the changeable elements in his verdicts. Hence, it is possible for the verdict of one mujtahid to change over time.
This is when the mujtahid is alive and has the ability to derive religious rulings from their sources and has a feel over religious rulings, their subjects, conditions, modifiers, and the change of conditions and modifiers. But, when the mujtahid dies or looses the ability to derive religious rulings from their sources, he is unable to change his verdicts along with the changeable elements. Therefore, it is almost unanimous amongst the jurists that it is not correct for someone to start their taqlid from this mujtahid and the continuance of taqlid for someone who has performed taqlid to this mujtahid during his lifetime is conditional upon the permission of a living mujtahid and one must perform taqlid to a living mujtahid on the new issues that occur. So, it is not correct to say that the verdict of a marja becomes invalid after his death, and even some high scholars such as Muhaqiq Qomi and Sharif al-Ulama (the teacher of Shaykh Ansari) believed that performing taqlid to the most knowledgeable dead marja to be permissible.
The condition of a marja being alive is the reason that Shiaism has stayed alive and grown by saying that it is not only a must for the mujtahid to be alive for his verdicts to be effective, rather, in addition to being alive, he must also have the ability to derive religious rulings and a healthy mind. Therefore, if a marja looses his mind one may not perform taqlid to him.
But, his verdicts are valid for those who have performed taqlid to him during his lifetime (with the permission of a living mujtahid). They also have an intellectual importance and are researched and used by scholars in their lessons.
It is better to complete the answer to this question with the words of Allamah Jawadi Amoli. He reasoned on this subject in the following manner:
An important problem to the permissibility of staying on the taqlid of a dead mujtahid is not that if a jurist dies his views also die and because of this one cannot perform taqlid to him. The reason it is not important is that death does not mean the destruction of one’s soul, rather death is the separation of one’s soul from his body. The body dies because it lost its caretaker; the soul does not die. Therefore, the person who made the verdict did not die.
So, there is no discussion over the fact that one who performed taqlid to a marja that has died has the permissibility to remain on his taqlid.
The main problem is this that according to a general principle, if the verdict of a marja changes one cannot act according to his previous verdict, rather he must act according to his new verdict. If a marja dies we do not know if his verdict would remain the same after his death when realities are shown to him, because after death all of the correct answers to religious problems would become clear for him. Before death he derived the verdict from the books, but after his death there are no more books, schools, or seminaries, rather the truth will be made clear for him. Hence, it is not known if his view after his death is the same as it was before or was changed due to a new issue. This is the main problem.
Another problem is this that the knowledge that a marja has which make his verdicts effective and those who perform taqlid to him perform it due to this knowledge is knowledge that has been gained from reason which was derived from the apparent meanings of the Quran and prophetic traditions, a consensus, or intellectual proofs; there is groundwork for ijtihad and there are principles that the mujtahid uses to dervie his rulings. But, when he leaves this world the knowledge that he has changes from being derived to being given. The knowledge that he learned from school is transformed into knowledge that he feels from his heart. The problem that arises is that if a jurisprudential matter is solved for a jurist by this method during his lifetime it might be a proof on him but would others be able to act in accordance to this verdict or not is the question.
The answer is that the verdict of the jurist is effective when it is derived from religious sources, but if a jurisprudential matter shown to someone as a result of purifying his soul, not from knowledge of jurisprudence and the principles of jurisprudence taught in religious seminaries it would not be capable of being followed. Because the jurist is seeing reality it is permissible for him to follow it. Of course there is a difference between the knowledge that is achieved at the start in a mystical way from the knowledge that is derived in the lifetime of the jurist by the ways that are taught in the seminary which are then transformed into given knowledge after death. In any case, the difference of opinion lies in this that after the death of a mujtahid or marja and the transformation of his knowledge, is one still able to act in accordance to his verdict; does the verdict remain or not?
The purpose of this is that if there is a discussion regarding remaining on the taqlid of a dead marja or similar subjects, it should not be considered that the body has a role in knowledge, rather it is the soul that has a role. The soul transforms gained knowledge into given knowledge after death and given knowledge is dependent on purifying one’s soul.