<P> The president exercises a check over Congress through his power to veto bills, but Congress may override any veto (excluding the so - called "pocket veto") by a two - thirds majority in each house . When the two houses of Congress cannot agree on a date for adjournment, the president may settle the dispute . Either house or both houses may be called into emergency session by the president . The Vice President serves as president of the Senate, but he may only vote to break a tie . </P> <P> The president, as noted above, appoints judges with the Senate's advice and consent . He also has the power to issue pardons and reprieves . Such pardons are not subject to confirmation by either the House of Representatives or the Senate, or even to acceptance by the recipient . The President is not mandated to carry out the orders of the Supreme Court . The Supreme Court does not have any enforcement power; the enforcement power lies solely with the executive branch . Thus, the executive branch can place a check on the Supreme Court through refusal to execute the orders of the court . For example, in Worcester v. Georgia, President Jackson refused to execute the orders of the Supreme Court . </P> <P> The president is the civilian Commander in Chief of the Army and Navy of the United States . He has the authority to command them to take appropriate military action in the event of a sudden crisis . However, only the Congress is explicitly granted the power to declare war per se, as well as to raise, fund and maintain the armed forces . Congress also has the duty and authority to prescribe the laws and regulations under which the armed forces operate, such as the Uniform Code of Military Justice, and requires that all Generals and Admirals appointed by the president be confirmed by a majority vote of the Senate before they can assume their office . </P> <P> Courts check both the executive branch and the legislative branch through judicial review . This concept is not written into the Constitution, but was envisioned by many of the Constitution's Framers (for example, The Federalist Papers mention it). The Supreme Court established a precedent for judicial review in Marbury v. Madison . There were protests by some at this decision, born chiefly of political expediency, but political realities in the particular case paradoxically restrained opposing views from asserting themselves . For this reason, precedent alone established the principle that a court may strike down a law it deems unconstitutional . </P>

The separation of powers in the national government outlined in the constitution is a foundation