Seoul Central District Court has ruled that saying "You are just like ‘Choi Soon-sil'" or "Are you f---ing Choi Soon-sil?" is defamatory.
Choi is a key suspect implicated in former President Park Geun-hye's corruption scandal.
The ruling involves two cases, argued last December, related to two colleagues from an office making fun of Choi's name.
The court fined a man surnamed Kim 1.5 million won ($1,310) for saying to his colleague,"You'd better quit this company because the truth has been coming out, unless you are ‘Choi Soon-sil.".
Kim also said to the co-worker,"You are spoiled because you grew up without your father."
The court also sentenced a man surnamed Ahn, to 10 months' jail for verbally abusing an acquaintance last November last year.
Ahn said in public, "You are just like Choi Soon-sil, because you extorted money from civilians."
The court took into account that Ahn has been jailed for violent crime many times.