Both theories—pluralism and elitism—address the way in which factions affect the democratic process. A faction is any group of individuals that works together to sway government choices in the democratic process. Examples of factions in the US include the two dominant political parties, Republicans and Democrats but also ancillary interest groups such as the National Rifle Association (NRA), Mother's Against Drunk Driving (MADD), the American Medical Association (AMA), and lobbying groups that support particular business interests. Further, demographic groups in society that commonly vote in the same way are considered factions, such as low-income individuals in urban areas, senior citizens, millennials, and so on.
The theory of pluralism holds that factions will balance each other out to result in a just democratic process. That is to say, because individuals can choose to support the faction of their choice, factions are a healthy part of democracy. An example of this occurred in the 1950s and 1960s, when the AMA, fighting against the tobacco lobby, successfully passed requirements that cigarette companies advertise the dangers of smoking.
The elite theory holds that factions do not necessarily reflect a healthy democracy because certain factions are more powerful than others. Consider recent attempts to pass clean energy legislation, universal healthcare, or gun control. Many argue that needed reforms have been stalled due the overwhelming influence of the oil lobby, the health insurance lobby, and the NRA being able to contribute more money to political campaigns than other factions. In other words, because certain factions reflect corporate interests that have far more ability give money to political leaders than the common citizen, they are unjustly empowered in the US democracy.
In the wake of the Citizen's United decision that gave factions the ability to make unlimited contributions to political campaigns, many contemporary theorists are concerned that the elite theory of democracy is dominating American politics and government—a trend that has many wondering at what point a democracy is better called corporate-ocracy.