Checks and balances, is when each branch of government ensures that the others fully meet their responsibilities and do not encroach on the powers of any other branch. Checks and balances recognize that ambitious politicians would almost certainly attempt to increase their power but would be restrained by other, equally ambitious politicians determined not to lose power.

Checks and balances were built into the Constitution to ensure that the powers of the three branches of government did not drift from one to another. With each branch having responsibility to monitor the powers of the other two, and to ensure that those powers were used appropriately, the relationships designed by the Founding Fathers would be maintained. In order to get things done, the three branches of government must cooperate. That is what the Founding Fathers wanted, to avoid too much power being vested in one branch of government. It would thus void what they most feared, which was tyranny. 

Examples of checks by the legislature on the executive branch of government are that they can amend/delay/reject the president's legislation. For example in 2001, Congress passed Bush's Education Reform Bill. They can also override the president's veto, for example Congress overrode 2 of Clinton's vetoes; one was the 1995 Securities Bill. Examples of checks by the legislature on the judiciary branch of government are that the Senate's power to confirm appointments made by the president, and another check is impeachment, trial, conviction and removal form office of any member of the judiciary. For example, between 1986 and 1989 Congress removed three federal judges from office: Harry Claborne fro tax evasion, Alcee Hastings for bribery and Walter Nixon for perjury. Examples of checks by the executive on the legislature branch of government are that they can recommend legislation. For example, in 2002, Bush focused on the war on terrorism and budget priorities in his speech. The President can also veto legislation passed by Congress, however Bush never used his power to veto legislation, whereas his predecessor Clinton vetoed bills passed by Congress 36 times. Examples of checks by the executive on the judiciary are the appointment of judges and pardon. An example of a check by the judiciary on the legislature branch of government is judicial review: the power to declare Acts of Congress unconstitutional. An example of a check by the judiciary on the executive branch of government is judicial review: the power to declare actions of any member of the executive branch, including the president, unconstitutional. For example, US vs Richard Nixon (1974), the Supreme Court ordered Nixon to hand over the white house tapes and to stop impeding the investigation of the Watergate affair. Nixon handed over the tapes and resigned within days, once the tapes involvement in an intricate cover up. 

Checks and balances arguably, are also seen as effective in some aspects. Checks and balances ensure that virtually all actions of the president would be subject to Congressional oversight. 'Power of the purse' (control over the budget), is arguably the most powerful tool Congress has in relation to the executive branch of government. Appointments to the Supreme Court, although initiated by the President, would be subject to the advice and consent of the Senate. Congress's performance would, in turn, be reviewed on a regular basis. All members of the lower chamber, the House of Representatives, would serve for two years and then face an election. Senators would serve for 6 years before facing reappointment by the state legislature. To ensure that the legislature itself did not become too powerful, its responsibilities were clearly defined in a long list of Section 8 in Article 1. Checks and balances ensure that the principle powers of the President in relation to the other branches of government would be the ability to veto Congressional legislation and to nominate justices to the Supreme Court. Because of the growth of the USA as a world power, the only expectations of the Founding Fathers, checks and balances on the President in the field of foreign affairs has arguably been on limited effectiveness. Checks and balances also ensure that the Supreme Court was given few constitutional powers and provided with no constitutional checks on the other branches. However, once in acquired the power of judicial review, enabling it to declare laws and presidential decisions unconstitutional, the judiciary gained one of the most powerful checks available to any of the branches of government. Judges, with the formidable power, are appointed for life and it is argued by some that this is the greatest weakness in the system of checks and balances.