The thesis analyses the moral hazard problem which arises in political or fiscal federations when member states anticipate being bailed out by the centre in case of financial distress. In particular, I examine whether an orderly default mechanism or deeper fiscal integration within the European Union can alleviate the soft budget constraint phenomenon and provide a solution to the sovereign debt crises engulfing the Eurozone and other parts of the world. The first essay adapts the standard Stackelberg approach of the bailout literature in order to study the effects of bankruptcy procedures on regional opportunistic behaviour. The insolvency mechanism is shaped by two parameters: the costs of default and the exemption level for public assets. The model lends support to the market discipline hypothesis if all public assets are exempt from seizure. If, by contrast, the exemption level for public assets is low, it is the central government rather than the credit market that discourages overborrowing since the former is incentivised to tax heavily indebted regions. The model's major policy insight is that an insolvency mechanism can lower the federation's welfare if it is not carefully designed. The second essay sheds light on the incentive effects of the sovereign debt restructuring mechanism which has been drafted by the Eurozone in response to the debt crisis. Employing a global game approach, the model analyses the impact of insolvency procedures on the size of the bailout, the level of effort exerted by the debtor country and EU welfare. Challenging some arguments in the policy literature, the model's major policy implication is that a half-hearted debt restructuring mechanism fails to mitigate the commitment and moral hazard problems embedded in the current EMU framework. The third essay questions the conventional wisdom that the Euro cannot survive without closer integration, using a simple political economy framework. The model compares the stability and welfare implications of the current "muddling through" scenario, an orderly default mechanism as well as a fiscal and a political union setting. Interestingly, the results suggest that the "muddling through" scenario is not more prone to break-up than the political or the fiscal union. The model's major policy recommendation is that implementing an orderly default mechanism and inserting an explicit exit clause into the European Treaties might prove more effective in preventing a Eurozone break-up than far-reaching institutional reforms.