Question:
What is the ruling on the divorce issued by an insane person (majnūn)?
Source: Fatāwā Amunpuri by Shaykh Ghulam Mustafa Zaheer Amunpuri
Answer:
A divorce given in a state of insanity does not take effect, whether written or spoken, because the insane person is not legally accountable (ghayr mukallaf) in that condition.
Scholarly Consensus:
❀ Ḥāfiẓ Ibn al-Mulaqqin رحمه الله (804 AH):
الإجماع قائم على أن طلاق المجنون والمعتوه غير واقع
“There is consensus that the divorce of the insane and mentally deranged does not take effect.”
(al-Tawḍīḥ, 25/287)

The divorce of an insane person is null and void by scholarly consensus, since he is not legally responsible during insanity.