The quote from the Declaration of Independence, "Governments are instituted among Men, deriving their just powers from the consent of the governed," reflects the Enlightenment idea of social contract theory. This theory suggests that government exists to serve the people and that the people have the right to alter or abolish government when it fails to fulfill its obligations.
This idea is reflected in modern government in many ways. Democracies around the world operate under the principle of popular sovereignty, meaning that government derives its authority from the people it governs. Many countries have written constitutions that establish the rights of citizens and limit the power of the government. Elections provide a way for citizens to express their consent or lack of consent for the government and its policies. In some countries, such as the United States, citizens have the right to petition the government for redress of grievances, another way to ensure that government is accountable to the people.