One of the main functions of the legislative branch is to exercise oversight over the actions of the executive branch. Under the mandate of representation granted to it by the people, parliament provides oversight of government accountability for its performance (actions and omissions),verifying and ensuring that government actions are consistent with society’s needs at all levels and do not exceed the powers and attributions conferred on it by law. The main objectives of parliamentary oversight can be described as follows:

• Detect and prevent abuse, arbitrary conduct, or unlawful and unconstitutional conduct by the government and public agencies. 
• Hold the government accountable for the use of taxpayers’ money. (For more information on this topic, see the “Open Budget” section.)
• Ensure that the policies announced by the government and approved by parliament are actually put into practice.
• Improve the transparency of government operations and increase public confidence in government.

Source: Hironori Yamamoto, Tools for Parliamentary Oversight. A Comparative Study of 88 National Parliaments, Inter-Parliamentary Union (2007).