United States
The justice system of the United States
How US federalism divides justice: reserved state powers, two separate court systems, and why most criminal justice is a matter for the states.
Facts on this page were checked against their sources on .
The starting point for the US justice system is not a grant of power to the centre but a reservation of power to the states. The Tenth Amendment reserves to the states, or to the people, every power not delegated to the federal government. The federal government’s authority over crime and justice is therefore the exception carved out by enumerated powers; the general authority is the states’.
- Two court systems
- The federal judiciary states that the federal government and each state government have their own separate court systems. Federal courts hear cases arising under the Constitution, federal law and treaties, disputes between states, admiralty, bankruptcy and habeas matters; state courts hear most criminal, contract, tort, family and probate cases.
- Federal structure
- Created under Article III, the federal system runs from the U.S. district courts, through the U.S. courts of appeals, to the Supreme Court of the United States. This is set out on the courts module.
- State variation
- Each state establishes its own courts through its own constitution and laws, and the systems vary. There is no single national template a state is required to follow.
AnalysisBecause most criminal law is state law, most of the justice system a person encounters — the police, the prosecutor, the trial court, the prison — is a state or local institution, not a federal one. The federal justice system is large and consequential, but it operates within enumerated federal competence rather than as the general criminal-justice system of the country.
The same idea, explained generally
- What is justice?
Justice is the principle that people should be treated according to rules that apply equally to everyone, decided by bodies that are authorised, constrained, and answerable. This guide explains what that means institutionally.
- What is the rule of law?
The rule of law is the principle that everyone, including the government, is subject to law that is public, applied equally, and interpreted by independent courts. This guide explains what it requires and what it does not.
- What do courts do?
Courts resolve disputes, test the state’s case against individuals, interpret law, and review public decisions. This guide explains those functions and why judicial independence is structural.
Sources
Sources
Tenth Amendment to the Constitution of the United States
Legal Information Institute, Cornell Law School (reproducing the enacted constitutional text) · Legislation · 1791-12-15 · link verified 2026-07-24
Verbatim text: 'The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people.' Supports the reserved-powers structure of US federalism — that the states, not the federal government, hold residual authority. Cornell LII reproduces the enacted text; the constitutional text itself is authoritative. Does NOT support any claim about how a particular power is allocated in practice.
Comparing Federal & State Courts
Administrative Office of the U.S. Courts (uscourts.gov) · Government publication · link verified 2026-07-24
The federal judiciary's own account. Supports: that the federal and state governments each have their own separate court systems; the federal structure of U.S. district courts, U.S. courts of appeals and the Supreme Court created under Article III; that each state establishes its own courts through its constitution and laws and that state systems vary; and the broad division of case types (federal courts hear cases on the Constitution, federal law, disputes between states, admiralty, bankruptcy, habeas; state courts hear most criminal, contract, tort, family and probate matters). Supports court STRUCTURE only; not caseload, effectiveness or the competence thresholds within any state.