What part of the constitution provides functional structure?

The functional structure of the U.S. Constitution is primarily outlined in its Articles, particularly Articles I, II, and III. Article I establishes the Legislative Branch, Article II outlines the Executive Branch, and Article III creates the Judicial Branch. Together, these articles define the powers, responsibilities, and limitations of each branch, ensuring a system of checks and balances. This framework is essential for maintaining the rule of law and preventing any one branch from becoming too powerful.