The Three Branches of Government.

The Constitution establishes a tripartite system of government, each branch with its distinct functions but interdependent on the others.

Legislative Branch (Congress).

The legislative branch, embodied by Congress, is vested with the power to make laws. It consists of two chambers: the House of Representatives and the Senate. The House is based on population representation, whereas the Senate represents states equally.

Congress's powers are extensive, including the authority to levy taxes, regulate commerce, declare war, and make all laws "necessary and proper" for executing its powers. However, its functions are not unlimited. For instance, Congress cannot pass ex post facto laws or bills of attainder and must adhere to constitutional rights and principles.

Executive Branch (President and Federal Agencies).

The executive branch is headed by the President, who holds the office for a four-year term. The President's primary role is to enforce and implement federal laws. This role includes commanding the armed forces, negotiating treaties (subject to Senate ratification), appointing federal officers and judges (with Senate approval), and ensuring the laws are faithfully executed.

The President also has the power to veto legislation, although Congress can override this veto with a two-thirds majority in both chambers.

Judiciary (Courts).

The judicial branch, led by the Supreme Court, is responsible for interpreting laws and adjudicating legal disputes. Its authority extends to cases arising under the Constitution, federal laws, treaties, maritime law, controversies to which the United States is a party, and between states or citizens of different states.

The judiciary's role in reviewing the constitutionality of legislative and executive actions (judicial review) is a critical aspect of its function, ensuring that all government actions comply with the Constitution.

Checks and Balances.

The system of checks and balances is integral to preventing any branch from gaining excessive power. This system ensures cooperation and competition among the branches, each with mechanisms to limit the others' powers.

Congress's Checks.

Congress can check the executive by overriding presidential vetoes, impeaching and removing the President or other high officials, and controlling appropriations and budgetary matters. It also has the power to confirm presidential appointments and ratify treaties.

Judicial appointments are subject to Senate confirmation, allowing Congress a say in the composition of the federal judiciary. Additionally, Congress can propose constitutional amendments and legislate to structure and limit the federal courts' jurisdiction.

Presidential Checks.

The President can check Congress through the veto power, influencing the legislative process. The President also has the authority to appoint federal judges, including Supreme Court Justices, shaping the judiciary's ideological balance.

Judicial Checks.

The judiciary can check both the legislative and executive branches through judicial review, declaring laws or executive actions unconstitutional. This power, though not explicitly stated in the Constitution, was established in Marbury v Madison and has been a fundamental aspect of judicial authority.

Executive Power and Authority.

Presidential powers are both broad and subject to checks. The President's role as commander-in-chief, while giving significant control over the military, does not extend to declaring war - a power reserved for Congress. The power to make treaties and appoint officials, while pivotal in foreign policy and government administration, requires the advice and consent of the Senate.

The President's power to issue executive orders, which direct the operations of the federal government, is a significant tool in shaping policy. However, these orders must be grounded in the Constitution or statutory authority and are subject to judicial review.