Which concept ensures that power is not concentrated in one branch of government?

The concept that ensures power is not concentrated in one branch of government is checks and balances. This principle is a foundational aspect of the United States Constitution, designed to prevent any one branch—executive, legislative, or judicial—from gaining too much power. Each branch has the ability to limit the powers of the others, ensuring that they can work together while also holding one another accountable.

For instance, the legislative branch makes laws, but the president can veto legislation, and the judicial branch can rule laws unconstitutional. This interdependence creates a system where cooperation is necessary, and it significantly reduces the risk of tyranny by any single branch.

In contrast, other options, such as federalism, refer to the division of power between national and state governments; popular sovereignty relates to the authority of the people in governance; and judicial activism describes a judicial philosophy where judges may interpret the Constitution more broadly. While these concepts are important facets of government structure, they do not specifically address the distribution of power among branches like checks and balances do.