Is it permissible for a woman to marry another man, having adopted the view of Ash-Shafi‘i concerning an invalid marriage—that it does not require a divorce or annulment—while knowing that she followed this view out of personal inclination?

A فاسد (corrupt/invalid) marriage is not permissible to continue. It has two scenarios:

First: If there is a consensus on its invalidity, such as marrying a fifth wife or a woman in her 'iddah (definition) (waiting period). In this case, there is no need for annulment (faskh (definition)) or divorce (talaq (definition)). The woman may marry another man immediately if no consummation occurred; otherwise, she must do so after observing a period of istibra' (ensuring no pregnancy).

Second: If there is a difference of opinion regarding its invalidity, such as a marriage without a guardian (wali) or without witnesses (ishhad). According to the majority of scholars, this requires annulment or divorce before the woman can marry another man. Otherwise, she would be sinful, and her marriage would be void.

Given this, there is no objection to adopting the view of Imam Al-Shafi'i through taqlid (definition) (following a qualified scholar). However, adopting it merely to seek concessions (tattabu' al-rukhas) is not permissible, and the one who does so is sinful. Such a person must repent, and one of the conditions for repentance is not to persist in that sin.

Therefore, one must not marry another man until an agreement for annulment is reached with the previous husband, if the invalidity of the marriage is not a matter of consensus, or until the matter is referred to a Sharia (definition) court for a ruling; for a judge's ruling resolves disputes.