Can Prime Ministers Constitutionally Deliberately Bankrupt their Countries?

In Ireland it is now clear that a decision by that country's Prime Minister to give an open ended pledge to back its banks will inevitably lead to the bankruptcy of the nation. In the UK the Prime Ministerial decisions over RBS, Northern Rock and the Prime Ministerial machinations regarding the takeover of HBOS by Lloyds will eventually be seen to have the same result. In the case of Gordon Brown, the sell off of national assets in the form of the Inland Revenue offices started way back in the last century. Illegal expenditure beyond Parliament's approval was identified by the National Audit Office as Parliament prorogued in July 2009 as I blogged here and here. What kind of democracies allow the PM and his Finance Minister to commit endless amounts of expenditure to crooks , spivs and cheats without any parliamentary review nor constitutional restraints. Such behaviour has to be illegal!