Brussels has rules on budget deficits, widely ignored by Spain, France, Greece, and historically even by Germany.

Brussels also has new rules on bank bailouts. Four times Brussels refused Italian Prime Minister Matteo Renzi's request for a state sponsored bailout of Italian banks because it's against the rules.

Renzi threatens to go ahead anyway. And if he does, who can stop him?

Please consider Renzi Ready to Defy Brussels and Bail out Italy's Troubled Banks.

Matteo Renzi, the Italian prime minister, is determined to intervene with public funds if necessary despite warnings from Brussels and Berlin over the need to respect rules that make creditors rather than taxpayers fund bank rescues, according to several officials and bankers familiar with their plans.