In discussing the separation of powers and the checks and balances that have been placed within the structure of government described by the U.S. Constitution, Publius does not actually mention the specific checks and balances used by the three branches of government. He argues instead by proving other forms of checks and balances to be ineffective, and by reassuring the reader that the proposed plan of government is well guarded by the diversity of the people, and the division of the people's authority among many channels of government.
The system of checks and balances placed in the U.S. Constitution is probably one of its most unique characteristics, and one of the reasons for the longevity of the government. Included within the Constitution are checks on the process of making a law, in which each branch can check the authority of the other. A bill can either originate in the executive or legislative branch, but must gain the approval of the other to continue onto a law. Even if the president vetoes a law, it can be approved by congress. The judicial branch guards against the constitutionality of all laws introduced either by the legislative or executive branch. There is never a time when the power to enact, execute and judge a law rests in one branch.
The system of checks and balances also serves to protect the United States from a military dictatorship while providing the advantages to a single commander in chief. Although the President is the Commander-in-chief during wartime, Congress is the only branch authorized to declare war, or to fund the army and navy. The strength of an executive branch, free to make war and ignore proposed legislation are clearly checked by the strength of Congress. If either the President or the legislative branch act in a way judged to be beyond their authority, the judicial branch can mark their actions as unconstitutional and prevent them from continuing.
Most of the checks built into the system are not specific as the ones relating to making laws and declaring war, but serve to generally delineate the lines of authority between the three branches. The judicial branch is the least described in the U.S. Constitution. Members of the judicial branch are appointed by the executive branch, with the approval of the legislative branch, can make final and absolute rulings on the actions of either the legislative or executive branch, and can only be removed from office by conviction of the legislative branch.
Although there are checks on the legislative branch, it has the least delineated checks on its authority because it most directly represents the people. It is the most accountable to the beliefs of the people, and this serves as an automatic check on its power. Representatives that serve in the House of Representatives are accountable every 2 years to their constituents in their individual state. They must always concern themselves with acting in a way dictated by the people or risk losing a re-election.
Publius referred to the practical problem of appealing to the people each time one branch encroached upon the powers of another. Since the legislative branch is the most powerful branch in a republic, it would most likely be the two other branches asking for an appeal. Then it would be like requesting the people, as represented by the legislative branch, to place a check on their own power. Trusting that the other checks in place, the executive branch to veto a piece of legislation and the judicial branch to declare it unconstitutional, such appeals to the people will not be necessary.
Furthermore, the people of the United States differ so drastically in their interests and opinions that they will be unable to act as a monolithic political force, and this brings greater safety to the nation. Competing interests will always serve to check one another's power because they jealously guard their own. In the same way as it would be unlikely for an executive to amass such a huge standing army as to become a military dictator, because it is checked by the legislative branch approving such measures, it would be unlikely for congress to successfully declare the presidency to be hereditary, because in addition to it being unconstitutional, not enough people would agree on this policy.
All of the checks placed on the government by the U.S. Constitution are improvements over the Articles of Confederation. Had the Confederation Congress been a stronger body, it could have easily amassed the executive, judicial and legislative powers into its own hands with no check on its authority but the resistance of the states. As it was the central government had no checks on the power of the states, either, but the states amassed a significant portion of the power under the Articles and left the central government weak.
The Constitution not only provides for checks between the branches of the central government, but checks between the state and federal systems of government, and a constant opportunity for the people to check the authority of the government through re-election. This creates the double protection that Publius referred to in the essays.