The market would not exert the same sort of pressure on Euro-bonds,

Ah. A percentage on the interest rate of the centrally emitted bonds.

Luis de Sousa:

That would also be the easiest way for a sovereign default within the Eurozone :) with an interest cap troubled states wouldn't find buyers for their bonds to roll-over debt and/or refinance their budgets.

By enforcing I meant something like this:

billy blog » Blog Archive » Why history matters

Prior to 1982, a tap system operated where the government would set the interest rate and then supply bonds to investors up to demand. Sometimes investors did not take up as much as the Government desired. The extra funds came from contra entries in the RBA-Treasury accounts (the government borrowing from itself!).