In many countries, the past few decades have been characterized by large budget deficits and excessive public debt levels, also outside of the financial crisis and the COVID-19 outbreak. However, sound fiscal policy is important for a healthy and stable economy. Fiscal discipline is therefore needed so that governments have room to stimulate the economy when it is struggling without jeopardizing the sustainability of public finances.In this thesis, I examine if fiscal rules can be of help. These rules impose constraints on fiscal policy, such as a limit for the budget deficit or a ceiling for public debt. The results show that fiscal rules are indeed desirable tools to reduce fiscal imbalances. Countries that adopt well-designed fiscal rule...