Is It Necessary to Verify If a Fatwā Has Changed?

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 5

As long as a person is not certain that the mujtahid’s fatwa has changed, he can act according to what is written in his manual of Islamic rulings. Furthermore, if a person deems it probable that a fatwa has changed, it is not necessary for him to investigate.

- Ayatullah Sistani, Practical Laws of Islam, Following a Jurist (Taqlid)