The country music star accuses Dan Dymtrow of using lawsuits 'to harass and cause grief' to her and her family.
She says Dymtrow, who managed Swift when she was 14 years old, ruined her 21st birthday by filing a lawsuit claiming she owed him millions of dollars in commission for playing a key role in the singer's career.
Now she has hit back with her own lawsuit - effectively suing him for suing her.
Swift's court action in Manhattan Federal Court accuses Dymtrow of having 'used the litigation process to attempt to harass and cause grief' to Swift and her loved ones.