How can consensus (Ijma') be determined in jurisprudential matters, especially when there are fatwas that contradict what is understood to be consensus, such as the issue of divorcing a menstruating woman?

If a consensus (Ijma') is established on a matter, it is not permissible to oppose it, based on the saying of Imam Al-Shafi'i: "And the command of the Messenger of Allah, may Allah's peace and blessings be upon him, to adhere to the community of Muslims: is among the arguments used to show that the consensus of the Muslims - Allah willing - is binding."

However, no consensus has been established regarding the occurrence of divorce during menstruation. Rather, there is an old disagreement on the matter, as some of the Salaf held the view that it does not occur. Among them are: Tawus ibn Kaysan, Khilas ibn Amr al-Hajari, Ibn 'Ulayyah, Dawud al-Zahiri, Ibn Hazm, and Ibn 'Aqil al-Hanbali. This view was also chosen by Shaykh al-Islam Ibn Taymiyyah and his student Ibn al-Qayyim, and it was preferred by later scholars such as al-San'ani, al-Shawkani, Ahmad Shakir, Ibn Baz, and Ibn 'Uthaymin.

Ibn Hazm and Ibn al-Qayyim refuted those who claimed a consensus on this matter, emphasizing that the disagreement on it is well-known and that the claim of consensus is false due to the absence of evidence for a definitive consensus that cannot be opposed.

Therefore, if no consensus is established on the matter, the problem is resolved, because what is forbidden is opposing a firmly established consensus.