Presidential systems possess several defining features including the separation of power between the executive and the legislative branches of government, weak party discipline, and a powerful committee system. Presidential systems, first devised in the United States as an alternative to the monarchical system, are characterized by a separation of powers. Not only do the executive and the legislature exist independently of one another, but they are also elected independently of one another. Moreover, those who are members of one cannot be members of the other. However, their overlapping responsibility for designing public policy often leads to competition and conflict between the two. This system encourages the fragmentation of power through the presence of checks and balances whereby each branch of government has some powers that intervene in the powers of the others. These features limit the powers enjoyed by each of the branches of government, however, they tend to mean that bills can be blocked at a variety of points and that comprehensive policies are difficult to achieve. There is generally a written constitution that defines the powers enjoyed by each branch of government, and that makes the presence of judicial review, whereby the courts review legislation to determine its constitutionality, a necessity.

Party discipline is weak under a presidential system, so party organization tends to be decentralized. Although political parties can be used to ease the tension and cooperation between the executive and the legislature, there is no guarantee that the party which holds the presidency will also control the legislature. Furthermore, voting in the legislature is more of an independent, rather than party affair. This means that the members of the legislature can be more constituency oriented.

The committee structure inherent in the presidential system provides another check on the power of political leaders and serves to weaken a leader's ability to control the legislature. This is because all bills must first be considered by committees which operate under an independent structure, often with investigative capabilities. These committees may alter a bill considerably before bringing it to the entire legislature for consideration. Since the power of the legislature is so diffused between the leaders, committees, and minority parties, there is no clear individual or group who can be identified as in control.

Policy leadership tends to rest with the office of the president because he/she is endowed with a personal mandate from the voters. In a presidential system, the symbolic and political aspects of the executive are fused: the president is both the head of state and the head of government. Since no other political official is directly elected by all the voters of the state, the president is seen to have a right of command to direct policy initiatives. Generally, the legislature acts in a responsive manner to bills put forward, or anticipated to be put forward, by the president. Through the president there is a clear focus of policy leadership. However, due to the committee system and the absence of party discipline in the legislature, final responsibility for particular policies is not clearly identifiable. To assist the president in his/her duties, he/she appoints a group of cabinet officials. These individuals tend not to be prominent political figures. In fact, they often come from backgrounds where they have had little political exposure.