Can a distinguished sage or nasi be placed under a ban?
The Rambam opens this chapter by stating that even a distinguished sage or nasi who acts shamefully is subject to ostracism. Nobody is above the law.
Question 2
What is the difference between nidui (ostracism) and cherem (excommunication)?
Nidui restricts social contact but allows teaching and commerce. Cherem is far more severe: no teaching, no learning from them, buying/selling limited to bare essentials.
Question 3
What happens if someone is ostracized for 30 days and doesn't seek release?
If the person doesn't seek release after 30 days, a second ban is issued. If still unresolved, escalation to full cherem (excommunication).
Question 4
How many people are needed to lift a ban?
Three people can lift a ban, and they don't need to be scholars. Even three common people suffice when no scholar is available.
Question 5
What happens when someone receives a ban in a dream?
The Rambam takes dream bans seriously: 10 people who are fit to teach halacha are required to release it. The subconscious has real halachic weight.