Sources of Law Annotate U.S. Constitution The Constitution is the supreme law

Sources of Law


U.S. Constitution

The Constitution is the supreme law of the United States of America. The first three articles of the Constitution establish the rules and separate powers of the three branches of the federal government: a legislature, an executive branch led by the President, and a federal judiciary headed by the Supreme Court. The last four articles frame the principle of federalism. 



The legislative branch of the United States, split between two powers (the Senate and the House of Representatives), checks and monitors the executive and judicial branches. The legislative branch passes bills, has broad taxing and spending power, controls the federal budget, and has power to borrow money on the credit of the United States. It has sole power to declare war, as well as the power to raise, support, and regulate the military. Further, the legislative branch is responsible for the ratification of treaties signed by the President and gives advice and consent to presidential appointments to the federal judiciary, federal executive departments, and other posts (Senate only). Lastly, the legislative branch has sole power of impeachment (House of Representatives) and trial of impeachments (Senate); it can also remove federal executive and judicial officers from office for high crimes and misdemeanors.



The president exercises a check over Congress through their power to veto bills, but Congress may override any veto by a two-thirds majority in each house of congress – the House of Representatives and the Senate. When the two houses of Congress cannot agree on a date for adjournment, the president may settle the dispute. Either house or both houses may be called into emergency session by the president. The vice president serves as president of the Senate, but he may only vote to break a tie.


The president appoints judges with the Senate’s advice and consent. They also have the power to issue pardons and reprieves. The president is the civilian Commander in Chief of the Army and Navy of the United States. It is generally understood that they have the authority to command them to take appropriate military action in the event of a sudden crisis. However, only the Congress is explicitly granted the power to declare war, as well as to raise, fund, and maintain the armed forces. Congress also has the duty and authority to prescribe the laws and regulations under which the armed forces operate, such as the Uniform Code of Military Justice, and requires that all Generals and Admirals appointed by the president be confirmed by a majority vote of the Senate before they can assume their office.



Courts check both the executive branch and the legislative branch through judicial review. This concept is not written into the Constitution, but it was envisioned by many of the Constitution’s Framers. Judicial review in the United States refers to the power of a court to review the constitutionality of a statute or treaty, or to review an administrative regulation for consistency with either a statute, a treaty, or the Constitution itself. The Supreme Court’s landmark decision on the issue of judicial review was Marbury v. Madison (1803), in which the Supreme Court ruled that the federal courts have the duty to review the constitutionality of acts of Congress and to declare them void when they are contrary to the Constitution. THe case of Marbury, handled by Chief Justice John Marshall, was the first Supreme Court case to strike down an act of Congress as unconstitutional. Since that time, the federal courts have exercised the power of judicial review.


Supreme Court: The Supreme Court holds the power to overturn laws and executive actions they deem unlawful or unconstitutional.


The judiciary branch also has involvement in the impeachment process of a president. The Chief Justice presides in the Senate during a president’s impeachment trial. The rules of the Senate, however, generally do not grant much authority to the presiding officer. Thus, the Chief Justice’s role in this regard is limited.


A discussion of judicial review and the common law leads to the concepts of precedent and stare decisis. When a case is decided, the decision is thereafter a precedent, that is, a reason for deciding a similar case the same way. There are two types of precedent—binding and persuasive. A binding precedent is a precedent that must be applied or followed by a court. It applies when a lower court is considering a case similar to a case previously decided by higher court in its jurisdiction. For example, a South Carolina Circuit Court is bound by a decision of the South Carolina Supreme Court, the highest court in the state. A persuasive precedent, on the other hand, is precedent that is not bound by a court decision, but may be relevant and used when considering a case. For example, a South Carolina Circuit Court is not bound by a decision of the Georgia Supreme Court, but may take the decision into consideration when deciding on a similar case. Stare decisis is the practice or policy of using precedent to decide cases; it means “let the decision stand.” Someone who supports stare decisis believes that courts should look to past cases to decide present controversies. U.S. Supreme Court Justice Kennedy stated in a 2010 landmark case that “[the US Supreme Court’s] precedent is to be respected unless the most convincing of reasons demonstrates that adherence to it puts us on a course that is sure error.” This is consistent with the Court’s long held view that “stare decisis is a principle of policy and not a mechanical formula of adherence to the latest decision.”


Law Sources

Executive Orders

In the United States, an executive order is an order or directive issued by the head of the executive branch at some level of government. The term executive order is most commonly applied to orders issued by the President, who is the head of the executive branch of the federal government. Executive orders may also be issued at the state level by a state’s governor or at the local level by the city’s mayor.




The president is the Commander-in-Chief of the nation’s armed forces. As the single officer of the United States charged with receiving the leaders of other nations and with negotiating treaties, the president is also the nation’s Chief Diplomat. In treaty making, the president must also work together with the Congress. Treaties are agreements between the United States and one or more other countries. While the president is free to negotiate treaties between the United States and other nations, treaties must be ratified by the Senate before they are officially binding on the United States.



Statutes, also known as acts, are laws passed by a legislature.  Federal statutes are laws enacted by Congress with (and in some circumstances, without) the approval of the president. Federal statutes are published in three formats:  (1) initially as individual slip laws, (2) in compilations of slip laws known as session laws, and (3) as codified law incorporated into a code.  Slip laws are individually paginated pamphlets, each containing a single statute.  Session laws compile the slip laws enacted in a session of Congress.  Codes are subject compilations of statutes in effect.  Federal slip laws, session laws, and codified laws are available in print and electronic sources.


Additional Resources

Chapter 5: Sources of Law

Chapter 11: Constitutional Law

References and Resources

Listed below are the references and resources used to curate this module.

Boundless (2020). Boundless Political Science. Lumen Candela. Retrieved from

Harris, Berger, et al. (2020). Sources of Law. Business Law Basics. Retrieved from

Legal Information Institute (2020). Citizens United v. Federal Election Comm’n. Cornell Law School. Retrieved from

Legal Information Institute (2020). Payne v. Tennessee. Cornell Law School. Retrieved from

Library of Congress (2015). Researching Federal Statutes. Library of Congress. Retrieved from

Lumen Learning (2020). American Government. Lumen Learning. Retrieved from

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