A fatwa is a formal religious ruling given by a qualified jurist in answer to a question of Islamic law. As a marja and jurist, Ayatollah Khamenei issued rulings that guided the religious practice of millions of followers.
Khamenei.ir maintains an official rulings service where his fatawa and juristic answers are published. The rulings summarized below come from that service.
A fatwa is different from a speech. A speech may teach or exhort, but a fatwa is binding religious guidance for those who follow the jurist.
His best-known ruling. He declared the use of nuclear weapons haram, and Iran's stated nuclear policy rested on this ruling for the rest of his leadership. He first announced the position publicly in 2003, and Iran presented it formally to the International Atomic Energy Agency in 2005.
In 2010 he prohibited insulting Aisha, the wife of the Prophet, and the other figures Sunni Muslims revere. The ruling answered a wave of sectarian provocation and was welcomed by Sunni scholars as a protection of Muslim unity.
He ruled against tatbir, the practice of striking the head with blades during Muharram mourning, calling it a fabricated tradition that harms Islam. The ruling changed mourning practice across much of the Shia world.
He ruled that invading people's privacy on social networks and internet messengers, including reading their messages without permission, is religiously forbidden.
During the COVID-19 pandemic he ruled that anyone whose health would be endangered by fasting is excused from it, and he accepted the suspension of congregational worship to protect lives.
As a marja, his rulings guided the religious practice of millions of followers.
Formal rulings are a small part of his public guidance.
His speeches and public teaching are covered on the Leadership and Sayings pages. The word fatwa is reserved for formal juristic rulings published through the official rulings service.