What We Talk About When We Talk About Law—United States Sources of Law

Hello, my wee pups, and join me for a breakdown of what I mean when I say “the law.”

We’re just covering United States federal law here, for simplicity’s sake. 1 This is purely for informational purposes and shouldn’t be construed as legal advice, and it’s an introduction at the most. They have entire grad schools just for explaining this stuff in enough depth to do anything with it.

In the United States, law comes from four primary sources: the Constitution, statutes, administrative law, and case law/common law. I’ll explain each briefly and where each party making these laws gets the right to do so, and I’ll link places you can find these laws to read for yourself.

1. The Constitution

First is the Constitution. It lays out the fundamental explicit powers of each branch of federal government and leaves the groundwork for implicit powers, as interpreted by the Supreme Court (see the section on case law below). Broadly speaking, if a government actor wants to take an action, e.g., pass a law, they have to derive the authority to do so from the Constitution, either explicitly or implicitly. In practice, this means that broadly speaking, if the Constitution or SCOTUS don’t say the federal government can do something, they can’t do it. There’s quite a lot of argument over the last two centuries over SCOTUS’ takes on implicit powers, so federal power has varied wildly over the course of its existence. The trend since the Civil War and the Great Depression has been to interpret the Constitution to allow the federal government more authority.

2. Statutes

The second body of law are statutes, as enacted by Congress. Established in Article I of the Constitution, Congress has its explicit powers did noted in article 1, section 8. I mentioned federal authority has greatly expanded as SCOTUS’s interpretation of the Constitution evolves—the understanding of what falls under the heading of “interstate commerce” and “tax” especially have expanded. 2

Federal legislation, once passed by Congress and signed or veto–overridden, is sent to the Office of the Federal Register, numbered, and published as slip law. 3 Slips are compiled at the end of each Congressional session and published as session law in the Statutes at Large. Slip and session laws are numbered and arranged chronologically in order of enactment.

Every six years, the House of Representatives’ Office of the Law Revision Counsel compiles general and permanent session law, organizes it by subject, and amends or revises the relevant Title of the United States Code. The USC is currently divided into 54 Titles by subject (with Title 53 reserved). Supplements are released annually between new additions. Not all slip and session laws are codified; private laws (as opposed to public laws) and time-limited legislation like annual budgets are not included in the USC. The United States Code is available online at uscode.house.gov or at www.law.cornell.edu/uscode/text.

3. Administrative Law

Third is administrative law and regulation, as promulgated by the executive branch under the president. 4

Administrative law is the body of rules and regulations set up by an administrative body, plus any executive orders or proclamations of the president. This all comes from the executive branch, which, if you remember your Constitution, doesn’t explicitly have the ability to pass law, so they get the authority to do so either by exercising a Constitutional power granted to the president and executive branch, or through a statutory grant of the authority by Congress in what’s called an “enabling act.” 5

Once an administrative body like the EPA gets the authority to pass regulations, it does so according to the requirements of the Administrative Procedure Act, a statute found at 5 USC § 551–559. Part of the requirements include a notice period where proposed regulations are presented to the public to allow commentary and discussion by the people to be affected by the proposed regulation. 6

Proposed and final regulations are published for public viewing in the Federal Register, a daily publication of governmental rules, regulations, and rulings. 7

Regulations are compiled annually from the Federal Register into the Code of Federal Regulations, or CFR. 8 The CFR basically stands as the equivalent to the United States Code, but for admin law instead of statute.

Executive orders, proclamations, and Executive Office of the President regulations are also published in the Federal Register and CFR. 9

More information on a specific administrative body, including internal structure, points of contact, how to make freedom of information act request, and other information can be found through the United States Government Manual. 10 Think of it like your car’s owner’s manual—if you see certain lights or alarms going off, it should tell you who to contact to get it taken care of.

4. Case Law

The fourth source of law is case law.

Case law and common law set precedent for enforcement and interpretation of statute and administrative law through the principle of stare decisis, or standing “by that which is already decided.” 11 12

All Supreme Court precedent is mandatory for inferior courts; Court of Appeals precedent is mandatory in its own circuit and merely persuasive in another circuits. District Courts are the federal-level trial court—the entry point into the court system—and set precedent only within their own jurisdiction. All other jurisdictions may find a persuasive but not mandatory.

There are federal and state level courts, and courts of varying jurisdiction on every level, so this is extremely cursory. Case law is constantly being updated because criminal and civil courts are always full, and there are a metric truckload of courts. I’ll revisit the topic of courts, because they’re a rich topic that I can’t cover in a quarter of a post.

There are a number of paid and free sources for keeping up with case law, and holy wars have broken out among lawyers over which of the paid services is the One True Source of Case Law. 13 For everyone else, Google Scholar keeps a relatively up-to-date, free to search and view legal database. I wouldn’t trust my life to it being totally up-to-date, But for preliminary research, it’s helpful.


I threw a lot of information at you today, and there’s a lot of reading you can do after this. My goal here was not to exhaustively explain every aspect of government, but to point you in a direction where you could find out from more on your own. 14 A responsible citizen is an informed citizen.

Until next time, sit. Stay. Speak. Good dog.


  1. Though with a book deal, I could be convinced to tackle all fifty states’ laws. It would take a lot of Euros to convince me to tackle another country’s laws.
  2. See, for example, the individual mandate of the Affordable Care Act—the penalty for not having medical insurance is considered by SCOTUS to be a tax, and therefore constitutional for Congress to pass.
  3. Available at Congress.gov/browse/all-congresses. As of this publication, the most recent statute passed is Pub. L. 115-390, Strengthening and Enhancing Cyber-capabilities by Utilizing Risk Exposure Technology Act, or SECURETA, available at Congress.gov/bill/115th-congress/house-bill/7327/text.
  4. “President of what?” — Snake Plissken, 1997.
  5. Not an enabling act like buying me dinner at a pizza buffet, but hey, feel free to offer.
  6. Absent good cause for haste, as described in § 553(b)(3)(A). Rulemaking procedure explained further at https://www.federalregister.gov/uploads/2011/01/the_rulemaking_process.pdf
  7. Available at govinfo.gov/app/collection/fr or federalregister.gov.
  8. Available at govinfo.gov/app/collection/cfr.
  9. The president’s non-regulatory documents like speeches are instead compiled at govinfo.gov/app/collection/cpd.
  10. Available at unitedstatesownersmanual.gov.
  11. Quidquim latine dictum sit, altum videtur.
  12. The Supreme Court assumed for itself the power to review existing law against the Constitution in a major power grab in Marbury v. Madison, but it seems to have worked out, so we let them continue. There’s much more to say on this another time.
  13. Westlaw 4 lyfe, unless Lexis wants to sponsor me.
  14. This is an old teacher trick—you go independently research the topic while I compulsively check my Twitter at my desk.

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