The executive branch has the responsibility to enforce the laws of the country as made and interpreted by the legislative and judicial branches, respectively. All three branches of government work in harmony within a system of checks and balances established to provide each branch with oversight of the others. The head of the executive branch is the president, who is elected for a maximum of two 4-year terms. Presidents can exercise a presidential veto, grant pardons, and negotiate treaties. However, there are also limitations to these powers, as a president does not have the authority to declare war. Furthermore, a president can be removed from office through the process of impeachment, which is initiated by the House of Representatives and is concluded by a trial in the Senate. Other important parts of the executive branch include the vice president and the Cabinet.