Defining the Fasiq and the Ruling on Backbiting

Question:
May Allah reward you. A set of questions. The first question says: What is the definition of the fasiq (open sinner)? And is it permissible to backbite him?

Answer:
The fasiq is the one who commits a major sin from the major sins, such as zina (unlawful sexual intercourse), theft, and drinking khamr (intoxicants), excluding shirk (associating partners with Allah). This is the fasiq. I am the first to see... And it is not permissible to backbite him.
Backbiting is forbidden, but if this is in the context of complaining to the one in authority, saying so-and-so did such-and-such, and so-and-so did such-and-such, in order to take action against him, so-and-so committed zina, so-and-so stole, so-and-so took such-and-such, in the context of seeking justice against him and returning injustices to their owners, then there is no harm in that. As for backbiting him in gatherings without benefit, this is not permissible. , this is general. It is only permissible for the wronged person to complain about his wrongdoer to the judge, to the qadi, to the prince, in order to obtain his right.
It is also permissible for the muhtasib, who is the one who enjoins good and forbids evil, to report on the perpetrators of crimes. Likewise, the security official; the security official is also required to report on the perpetrators of crimes in order to take action against them, to purify the society from their evil. So if the backbiting is for a stronger benefit, there is no harm. But if the backbiting is for no benefit or a small benefit, it remains forbidden and is not permissible, and there is no benefit in it either. If you speak about so-and-so in gatherings, what results from this? Will he be taken to account? Will he be prevented? Does anything result from this?