Qualifications of Mass prayer leader

1474. The Imam of the congregational prayers should be:
Adult (Baligh); sane; Ithna ‘Ashari Shi’ah; Adil; of legitimate birth; and beig able to offer the prayers correctly. Furthermore, as an obligatory precaution, the Imam also should be a male.
There is no harm if a discerning child, one who is able to distinguish good from evil, follows another discerning child.

1475. If a person who once considered an Imam to be Adil, doubts whether he continues to be Adil, he can follow him.

1476. A person who offers prayers standing, cannot follow a person who offers his prayers while sitting or lying, and a person who offers his prayers while sitting, cannot follow a person who offers his prayers while lying.

1477. A person who offers prayers sitting, can follow another person who offers his prayers while sitting. But if a person offers prayers while lying, for him to follow a person who offers prayers in sitting or lying position is not in order, as an obligatory precaution

1478. If Imam, because of some excuse, leads the prayers with Tayammum, or Jabira Wudhu, it is permissible to follow him; but if he leads the prayer in a Najis dress because of some excuse, as an obligatory precaution, it is not permissible to follow him.

1480. As an obligatory precaution, a preson who is suffering from blotches or leprosy and a person who has been subjected to Islamic Haad (punishment according to Shariah) should not lead congregational prayers.