Lord Black has fired back at several of his biggest critics at Hollinger International by filing a lawsuit in Toronto claiming that they have defamed him.
Among the defendants named in the suit are Richard Breeden, a former chairman of the Securities and Exchange Commission.
He has been advising a group of Hollinger International directors who have accused Lord Black of misappropriating millions of pounds.
Other defendants include Gordon Paris, who has replaced Lord Black as chairman and chief executive of Chicago-based Hollinger International, Lord Black's newspaper operating company.
The suit also names former Illinois governor James Thompson and three other independent directors of Hollinger International.
The suit claims a total of £361 million in damages for defamation, conspiracy to injure, interference with economic relations and intimidation, intentional misrepresentation, plus punitive damages.