<P> Supporters generally claim four basic advantages for presidential systems: </P> <Ul> <Li> Direct elections--in a presidential system, the president is often elected directly by the people . This makes the president's power more legitimate than that of a leader appointed indirectly . However, this is not a necessary feature of a presidential system . Some presidential states have an indirectly elected head of state . </Li> <Li> Separation of powers--a presidential system establishes the presidency and the legislature as two parallel structures . This allows each structure to monitor and check the other, preventing abuses of power . </Li> <Li> Speed and decisiveness--A president with strong powers can usually enact changes quickly . However, the separation of powers can also slow the system down . </Li> <Li> Stability--a president, by virtue of a fixed term, may provide more stability than a prime minister, who can be dismissed at any time . </Li> </Ul> <Li> Direct elections--in a presidential system, the president is often elected directly by the people . This makes the president's power more legitimate than that of a leader appointed indirectly . However, this is not a necessary feature of a presidential system . Some presidential states have an indirectly elected head of state . </Li> <Li> Separation of powers--a presidential system establishes the presidency and the legislature as two parallel structures . This allows each structure to monitor and check the other, preventing abuses of power . </Li>

What form of government is characterized by the separation of powers