Types of U.S. Legal System
The United States operates one of the most structurally complex legal systems in the world, built on a dual-court architecture that distributes authority across 51 distinct jurisdictions — 50 states plus the federal government. Understanding the major categories of U.S. law, how courts are classified, and where one type of legal matter ends and another begins is foundational to navigating any legal question accurately. This page maps the primary types within the U.S. legal system, identifies the boundaries between them, and clarifies the misclassifications that arise most often in practice. For a broader orientation, the U.S. Legal System Overview provides the structural baseline from which these distinctions extend.
Substantive Types
The U.S. legal system divides into categories along two primary axes: the source of authority (federal vs. state) and the nature of the dispute (civil vs. criminal, public vs. private). These axes generate at least 6 operationally distinct legal domains, each with its own procedural rules, evidentiary standards, and institutional actors.
1. Federal Law
Federal law derives from the U.S. Constitution, Acts of Congress, federal regulations codified in the Code of Federal Regulations (C.F.R.), and federal common law developed through Article III courts. The federal judiciary — governed under Title 28 of the United States Code — includes 94 district courts, 13 circuit courts of appeals, and the Supreme Court. Federal subject-matter jurisdiction is constitutionally limited; it attaches when a case involves a federal question (28 U.S.C. § 1331) or diversity of citizenship with an amount in controversy exceeding $75,000 (28 U.S.C. § 1332).
Federal legal matters encompass bankruptcy (11 U.S.C.), immigration (8 U.S.C.), intellectual property, securities regulation under the Securities Exchange Act of 1934, and civil rights enforcement under 42 U.S.C. § 1983. The Regulatory Context for the U.S. Legal System page details how federal agency rulemaking generates binding legal obligations distinct from congressional statutes.
2. State Law
State law governs the overwhelming majority of legal disputes that individuals encounter: contracts, torts, property, family matters, criminal offenses below the federal threshold, and most business disputes. Each state maintains its own constitution, statutory code, and common law tradition. Louisiana operates under a civil law system derived from the Napoleonic Code rather than English common law — making it structurally distinct from the other 49 states.
State-level legal frameworks vary significantly in procedural and substantive rules. Alabama Legal Services Authority covers Alabama-specific legal procedures and the state court hierarchy governing civil and criminal matters there. Alaska Legal Services Authority addresses Alaska's unique jurisdictional complexities, including its specialized tribal court relationships. Arizona Legal Services Authority maps Arizona's court structure, including its justice courts handling disputes under $10,000. Arkansas Legal Services Authority documents the statutory framework governing civil litigation and criminal procedure in Arkansas circuit courts.
3. Civil Law (Private Disputes)
Civil law governs disputes between private parties — individuals, corporations, or government entities acting in a non-prosecutorial capacity. The plaintiff bears the burden of proving their case by a preponderance of the evidence (more likely than not, i.e., greater than 50%). Remedies are typically monetary damages or equitable relief such as injunctions.
Civil law subdivisions include tort law (negligence, strict liability, intentional torts), contract law, property law, family law, and probate. The Process Framework for the U.S. Legal System outlines how civil cases move from complaint filing through discovery, trial, and appeal.
California Legal Services Authority is an essential resource for California civil procedure, covering the state's unique rules under the California Code of Civil Procedure. Colorado Legal Services Authority addresses civil litigation in Colorado's district courts, including small claims procedures capped at $7,500. Connecticut Legal Services Authority covers Connecticut's Superior Court system, which handles civil disputes, family matters, and criminal cases under a unified structure.
4. Criminal Law
Criminal law involves the prosecution of individuals or entities by a government body — federal, state, or local — for conduct defined as an offense against society. The prosecution must prove guilt beyond a reasonable doubt, the highest evidentiary standard in U.S. law. Convictions may result in incarceration, fines, probation, or capital punishment where permitted by state statute.
The distinction between felonies (typically punishable by more than 1 year of imprisonment) and misdemeanors structures criminal procedure at every level. Federal criminal law is codified primarily in Title 18 of the U.S. Code. Delaware Legal Services Authority covers Delaware's Court of Common Pleas and Superior Court criminal divisions. Florida Legal Services Authority documents Florida's criminal statute framework, including its habitual offender sentencing enhancements under Florida Statutes § 775.084. Georgia Legal Services Authority maps Georgia's bifurcated criminal court system, where superior courts handle felonies and state courts handle misdemeanors.
The Criminal Defense Authority Vertical Group aggregates resources across jurisdictions for criminal defense-specific procedural and substantive law.
5. Administrative Law
Administrative law governs the authority and actions of federal and state agencies. At the federal level, the Administrative Procedure Act (APA), codified at 5 U.S.C. §§ 551–559, establishes the framework for agency rulemaking, adjudication, and judicial review. Federal agencies — including the Environmental Protection Agency, the Social Security Administration, and the Internal Revenue Service — exercise quasi-legislative and quasi-judicial powers that generate enforceable obligations outside traditional court processes.
State administrative law mirrors federal APA structures, though procedural rules differ across jurisdictions. Hawaii Legal Services Authority covers Hawaii's administrative hearing procedures under the Hawaii Administrative Procedure Act. Idaho Legal Services Authority documents administrative appeals processes before Idaho state agencies. Illinois Legal Services Authority addresses Illinois administrative law, including hearings before the Illinois Human Rights Commission.
The IRS Resolution Authority Vertical Group focuses specifically on federal tax administrative proceedings, including Collections Due Process hearings and offers in compromise governed by Internal Revenue Code § 7122.
6. Constitutional Law
Constitutional law interprets the U.S. Constitution and its 27 amendments as the supreme law of the land under the Supremacy Clause (Article VI, Clause 2). It governs the limits of governmental power and the protection of individual rights. Constitutional claims arise in both civil and criminal contexts — most frequently in cases involving the First, Fourth, Fifth, Sixth, and Fourteenth Amendments. Marbury v. Madison (1803) established judicial review as the mechanism by which courts strike down unconstitutional statutes.
The National Civil Rights Authority resource group covers constitutional civil rights claims, including equal protection challenges and due process violations under the Fourteenth Amendment.
Where Categories Overlap
Legal matters frequently implicate more than one category simultaneously, and practitioners must identify which body of law controls each element of a dispute.
Criminal-Civil Overlap: The same underlying conduct can generate both criminal prosecution and civil liability. A driver charged with vehicular manslaughter under state criminal law may simultaneously face a wrongful death tort suit by the victim's estate. The two proceedings are legally independent: the criminal acquittal does not bar civil recovery because the evidentiary standards differ (beyond a reasonable doubt vs. preponderance). O.J. Simpson's 1994–1997 cases are the most widely cited public illustration of this dual-track structure.
Federal-State Concurrent Jurisdiction: For certain offenses and civil claims, both federal and state courts have subject-matter jurisdiction. Drug trafficking offenses may be prosecuted under federal law (21 U.S.C. § 841), state law, or both — the Double Jeopardy Clause does not bar successive federal and state prosecutions under the separate sovereigns doctrine affirmed in Gamble v. United States, 587 U.S. 678 (2019).
Administrative-Civil Overlap: Employment discrimination claims under Title VII of the Civil Rights Act of 1964 require exhaustion of administrative remedies before the Equal Employment Opportunity Commission (EEOC) prior to filing a civil lawsuit. The administrative proceeding is a mandatory prerequisite, not an alternative forum.
Indiana Legal Services Authority covers Indiana's overlap between state administrative agency decisions and civil court review. Iowa Legal Services Authority documents Iowa's workers' compensation system, where administrative adjudication precedes circuit court review. Kansas Legal Services Authority addresses the interplay between Kansas administrative proceedings and district court appeals under the Kansas Judicial Review Act (K.S.A. § 77-601 et seq.).
Kentucky Legal Services Authority maps how Kentucky's circuit and district courts handle overlapping civil and domestic relations matters. Louisiana Legal Services Authority is particularly important for civil law practitioners, given Louisiana's hybrid legal system that blends civilian and common law traditions — the only such structure among all 50 states.
The How the U.S. Legal System Works conceptual overview provides the architectural context for understanding how these overlapping domains interact institutionally.
Decision Boundaries
Determining which legal category governs a specific matter — and which court or agency holds jurisdiction —