Commander in Chief

• While only Congress has the authority to declare war, the president is commander in chief of the armed forces. Constitutionally, his freedom to act is checked by Congress's decisions. Strategic decisions, however, are his once Congress has permitted the war. The president also retains the power to call the National Guard into action. He is the only person with authority to implement the use of nuclear weapons in a military action.
  
  

Reprieves and Pardons

• The Constitution states that "he shall have the power to grant reprieves and pardons for offences against the United States." This act can be directed towards individuals as well as towards groups of people. Persistent controversy has surrounded this diplomatic power, whether used by Republican or Democratic presidents. Constitutionally it is understood not as a personal act, but as an act on behalf of the public good.
  
  

Power to Make Treaties

• The three branches of government provide checks and balances.Jupiterimages/Photos.com/Getty Images
  
  The president's role as head of state is occupied largely in dealing with foreign affairs. Similar to his checked powers as commander in chief, he has the "power, by and with the advice and consent of the senate, to make treaties, provided two thirds of the senators present concur." Again, once the Senate has ratified a treaty it becomes legal. The president is responsible for contact with foreign governments, therefore the diplomatic power to decide on details within the treaty is chiefly his.
  
  

Nominate and Appoint

• The president's powers include appointments to the supreme court.Tom Brakefield/Stockbyte/Getty Images
  
  Once he has gained the Senate's consent, the president can "appoint ambassadors, other ministers and consuls, judges of the Supreme Court and all other officers of the United States." These nominations and appointments permit the president some freedom to follow a certain ideological course. Achieving Senate or Congress consent is rarely an easy matter. When it comes to notable appointments, like the Supreme Court, the president's diplomatic power can have lasting ramifications on the shape and course of the judiciary.
  
  

Fill Up Vacancies

• The president has the power to "fill up all vacancies that may happen during the recess of the Senate." Usually, such appointments require confirmation by the Senate, but while it is in recess, the president can act individually. As a diplomatic power, it is an opportunity for the president to make appointments that would not usually get past the Senate's ratification.