LawShelf courses have been evaluated and recommended for college credit by the National College Credit Recommendation Service (NCCRS), and may be eligible to transfer to over 1,300 colleges and universities.

We also have established a growing list of partner colleges that guarantee LawShelf credit transfers, including Excelsior University, Thomas Edison State University, University of Maryland Global Campus, Purdue University Global, and Southern New Hampshire University.

Purchase a course multi-pack for yourself or a friend and save up to 50%!
1-year bachelor's

Sources of Law in the United States

See Also:

Sources of Law


Laws are the rules of conduct established to maintain stability and justice in a community. When taking the oath of office on August 9, 1974, President Gerald Ford referred to the United States’ government and political framework by stating “Our great republic is a government of laws and not men.

Laws provide ways for our society to resolve disputes civilly and ensure a peaceful and well-functioning society.

In this presentation, we will examine the four primary sources of law at the state and federal levels. These four sources of law are the United States Constitution, federal and state statutes, administrative regulations, and case law.

United States Constitution

Each country’s legal system has its own sources of law, but for those systems that enact Constitutions, the Constitutions are the most fundamental of the sources of law.[1] A Constitution is a charter that establishes the government and the rules under which the government must run.

The United States Constitution, therefore, is our “supreme law of the land” (in its own words). Everything within it is binding. Think of the constitution as the “ultimate” source of law, the source that all others draw from. Federal statutes, state statutes, judicial opinions and administrative laws must all comply with the Constitution’s rules.[2] The U.S. Constitution is internationally revered for its organization, its subject matter and its groundbreaking nature at the time it was ratified.[3]

The Constitution both establishes the rules for the functioning of the United States government and sets forth the fundamental freedoms and rights that each person enjoys.[4] While the Articles are mostly about the functioning of the government, the first ten amendments to the Constitution make up the “Bill of Rights,” which protect individual liberties. For example, the First Amendment prohibits Congress from making laws that abridge freedom of speech. The Second Amendment prohibits infringement on the right to keep and bear arms and the Fourth Amendment guarantees a person’s right to be secure against unreasonable searches and seizures. Over the last 230 years, how these amendments are applied in our society has evolved, but their foundational protections have remained steady.

The Constitution also discusses the power and responsibility of the government and provides guidance on how the government is organized. The first three articles describe the structure and scope of the federal government. Article I establishes the structure and powers of the Congress. Article II describes the executive branch of government, specifically delineating the roles of the President and Vice President. Article III establishes the judicial power of the federal courts.

Federal and State Statutes

Federal and state legislation, also known as statutory law, is the second important source of law in our legal system.

The United States Congress enacts federal statutes and these statutes apply in all 50 states. An example of a federal statute is the Clean Air Act, a federal law that regulates air emissions from stationary and mobile pollution sources. That act is a federal law and as such, it applies to every stationary and mobile source of air pollution in every state across the country.

Federal statutes passed during a legislative session are published in the United States Code, which is broken down into titles, with each title tackling a different subject matter. For example, Title 11 covers bankruptcy, Title 18 covers federal crimes and Title 26 covers taxes.

State statutes are enacted by state legislatures and apply only within the state. Though they regulate activity within a state, they must give way to federal statutes in cases of conflict. The United States Constitution’s “supremacy” clause, Article VI, Clause 2, provides that the Constitution and the federal laws are “the supreme Law of the Land.”[5] State statutes that conflict with federal law are “preempted.”

Administrative Regulations

            Administrative regulations are rules issued by state or federal administrative agencies. Examples include the Environmental Protection Agency and Internal Revenue Service. These regulations provide the rules for how a law will be applied and enforced. Federal agencies developing regulations receive their authority to regulate and enforce from Congress, through an “enabling” act, which grants and defines the scope of its authority.[6]

            At the federal level, administrative regulations are published and updated annually in three different places:

·         The Code of Federal Regulations which are the main source of regulatory laws;

·         The List of Sections Affected, which are brief summaries of affected sections of federal law; and

·         The Federal Register, which are detailed explanations of the regulations.[7]

Administrative regulations are developed through two types of rulemaking, informal and formal. Under informal rulemaking, an agency proposes a rule, the public submits written comments and then the agency decides how to create a final rule.[8] Informal rulemaking is more fluid and requires an agency to provide general notice with the time, place, and nature of the proceeding so that the public can comment on the proposed rules. In formal rulemaking, administrative agencies can issue regulations after meeting certain procedural requirements under the Administrative Procedure Act. That Act stipulates that the proponent of a rule carry the burden of proof that the necessary steps were complied with. As such, formal rulemaking can be costly and time consuming.

Case Law and Judicial Opinions

            Judge-made law, known as case law, is also sometimes referred to as the “common law.” Legislatures may write broad statutes and allow judges to interpret the meanings of the laws by applying them to cases involving real people and businesses. Alternatively, issues can come up that have not been dealt with by statutes. In such cases, courts can apply definitions and rules based on the traditional way these matters have been dealt with. For example, state law rarely defines the elements of torts or the building blocks of contracts. These are matters that are defined based on tradition, dating back centuries, often to English law.

Once a court renders a decision, its decision, or “opinion” becomes precedent that must be applied in subsequent factual scenarios. When a court uses rulings from prior cases to reach a decision, it is abiding by the principle of stare decisis. Stare decisis promotes evenhanded and predictable application of laws.[9] However, not every court is required to follow the decisions of every other court. Courts only need to follow the decisions of appellate courts within their own system. The decisions of other courts may be “persuasive” authority but are not “mandatory” authority. For example, the New Jersey state court must follow the decisions of the New Jersey Supreme Court, but need not follow the decisions of other lower-level New Jersey courts or even of the Pennsylvania Supreme Court.[10]

The federal court system also has trial courts and appellate courts. The trial courts are called “district” courts. Appellate courts to which trial court decisions can be appealed are known as the “circuit” courts of appeal. Circuit court decisions can be appealed to the United States Supreme Court. So, for example, a Second Circuit Court of Appeals decision must be followed by a federal court in Vermont since Vermont is in the Second Circuit. Vermont courts are not obligated to follow decisions from the First or Third Circuit Courts of Appeals. All these courts (and, in fact, all courts in the country) are required to follow decisions by the United States Supreme Court.

Over two centuries, the United States’ legal system has become a model for other nations across the world, which seek to develop a diverse array of laws. In this presentation, we’ve discussed the four sources of law that interact, overlap, and work in conjunction with one another to create a robust set of legal guidance.


[3] Edwin Meese III, “The Meaning of The Constitution,” http://www.heritage.org/political-process/report/the-meaning-the-constitution.

[4] Robin Welford Slocum, Legal Reasoning, Writing, and Other Lawyering Skills, (2011).

[5] Jean Eggen, “The Normalization of Product Preemption Doctrine,” 57 Ala. L. Rev. 725, (2006).

[8] Aaron Nielson, “In Defense of Formal Rulemaking,” 75 Ohio St. L.J. 237, (2014).

[10] “Common Law” Bouvier Law Dictionary; “Precedent” Bouvier Law Dictionary