Is a wicked person's backbiting not considered backbiting, and what is the definition of wickedness, and how is one judged to be wicked, and is persistence in minor sins considered wickedness?

The transgressor (fasiq) is one who commits a major sin and does not repent, or one who persists in minor sins. Backbiting (gheebah) is forbidden by Islamic law, and this applies to both the transgressor and the obedient. However, backbiting a transgressor is permissible if there is a legitimate, recognized Sharia interest, not for vindictiveness, such as warning others about him if publicizing his transgressions deters him from sins. As for one who does not openly commit sins, the principle is to conceal his faults and admonish him privately. It is permissible to publicize the transgression or innovation of one who openly commits them, but not what he does not publicize, so that he and others may be deterred. Backbiting is permissible for warning against transgression or innovation, or when complaining about an oppressor, or when giving a fatwa, or for identification by a nickname if there is no other way, and for speaking the truth when giving advice. However, if someone openly commits a sin and is a scholar whose example is followed, backbiting him is not permissible, so that people do not become lenient regarding sin.