Earlier this month, Finance Minister Vic Fedeli demanded an apology and a retraction from former PC Leader, turned Brampton Mayor Patrick Brown.
Now, Fedeli has filed an $8 million lawsuit.
It's over claims in Brown's recent book, including allegations of workplace sexual harassment.
It also accuses Brown of making other, "false and defamatory statements," and mounting a, "vicious and petulant attack."
The lawsuit names Brown and his publishers.
The claims have not been tested in court.