## Introduction

Article III establishes the federal judicial branch. It creates the Supreme Court, allows Congress to set up lower federal courts, spells out which cases federal courts can hear, guarantees jury trials in federal criminal cases, and defines treason. This guide breaks down the text of Article III, shows how it works through landmark cases, and offers practical takeaways for students, lawyers, and anyone interested in how federal courts operate.

## What You'll Learn

- What Article III says in Sections 1–3
- How federal court jurisdiction works (federal questions, diversity, admiralty, and more)
- The difference between original and appellate jurisdiction in the Supreme Court
- The jury trial guarantee in federal criminal cases
- How treason is defined and proven
- The role of judicial review and checks and balances
- Standing and the “case or controversy” requirement
- Landmark Article III cases and why they matter
- Practical steps to assess whether a dispute belongs in federal court

## Core Concepts

### Section 1: The Federal Judiciary

- Creates the Supreme Court and authorizes Congress to establish inferior federal courts (for example, courts of appeals and district courts).
- Judges hold their offices during “good behavior,” which in practice means life tenure unless impeached and removed.
- Judicial salaries cannot be reduced while judges are in office.
- Why it matters: Life tenure and salary protection help keep federal judges independent from day-to-day political pressure. Congress decides the number and structure of lower courts and has set the size of the Supreme Court by statute.

### Section 2: Judicial Power and Jurisdiction

Article III extends federal judicial power to specific categories of cases and controversies, including:

- Cases arising under the Constitution, federal laws, and treaties (federal question jurisdiction).
- Cases affecting ambassadors, public ministers, and consuls.
- Admiralty and maritime cases.
- Controversies to which the United States is a party.
- Controversies between two or more states.
- Controversies between citizens of different states (diversity jurisdiction).
- Certain disputes involving states or foreign parties.

Key points:

- Supreme Court jurisdiction: The Court has original jurisdiction in limited categories (for example, cases involving ambassadors and disputes where a state is a party) and appellate jurisdiction in most others, subject to “exceptions and regulations” set by Congress.
- Eleventh Amendment note: Suits against states by private citizens are limited, which affects some categories listed in Article III.

### Trial by Jury in Federal Criminal Cases

Article III guarantees:

- A jury trial for all federal crimes except impeachment.
- Venue in the state where the crime was committed. If the crime was not committed within any state, Congress may designate the place of trial.
- The Sixth Amendment later adds more detail (impartial jury, speedy trial, and other rights). In practice, a jury may be waived only under strict procedures set by federal rules and case law.

### Section 3: Treason

- Definition: Treason against the United States consists only of levying war against the United States, or adhering to their enemies by giving them aid and comfort.
- Proof: No conviction without testimony of two witnesses to the same overt act, or confession in open court.
- Punishment: Set by Congress, but no “corruption of blood” (punishing descendants) or forfeiture beyond the life of the person convicted.

### Standing and the Case-or-Controversy Rule

Article III allows federal courts to decide actual disputes, not hypothetical questions. Core justiciability limits include:

- Standing: A plaintiff must show a concrete and particularized injury, that the injury was caused by the defendant, and that a court ruling can likely remedy it.
- Ripeness and mootness: Courts avoid cases that are too early (not ready for review) or no longer live.
- Advisory opinions: Federal courts do not issue advisory opinions.
- Political questions: Some issues are committed to the political branches and are not for courts to decide.

## Key Examples or Case Studies

Example 1: Federal question jurisdiction in action

- Scenario: A federal district court hears a case about the meaning of a federal statute.
- Why it matters: Article III and 28 U.S.C. § 1331 permit federal courts to interpret and apply federal law, helping keep federal law consistent nationwide.

Example 2: Trial by jury in a federal criminal case

- Scenario: A defendant charged with a federal felony invokes the right to a jury.
- Why it matters: Article III guarantees a jury in federal criminal cases (aside from impeachment), with venue in the state where the crime occurred.

Marbury v. Madison (1803)

- Context: A dispute over judicial commissions led the Supreme Court to define its role under the Constitution.
- Holding: The Court announced the power of judicial review—the authority to invalidate laws or actions that conflict with the Constitution.
- Why it matters: Judicial review is central to checks and balances and is rooted in Article III’s judicial power.

Ex parte Milligan (1866)

- Context: A civilian was tried by a military commission while civilian courts were open.
- Holding: The Supreme Court ruled that trying civilians in military courts is unconstitutional when civilian courts are operating.
- Why it matters: Reinforces the role and jurisdiction of Article III courts, even in wartime.

Brown v. Board of Education (1954)

- Context: Families challenged state laws mandating racially segregated public schools.
- Holding: The Supreme Court declared such laws unconstitutional under the Fourteenth Amendment.
- Why it matters: Shows judicial review in practice and how Article III courts protect constitutional rights.

Lujan v. Defenders of Wildlife (1992)

- Context: Environmental groups challenged a federal rule but could not show concrete injury.
- Holding: The Court dismissed the case for lack of standing.
- Why it matters: Clarifies that Article III requires a real injury that a court ruling can address.

## Practical Applications

- Confirm federal subject-matter jurisdiction before filing:
  - Federal question: Does the claim arise under the Constitution, federal statute, or treaty?
  - Diversity: Are the parties citizens of different states and is the amount in controversy met?
  - Admiralty, the U.S. as a party, or disputes between states may also qualify.

- Assess standing and justiciability:
  - Identify a concrete injury, causation, and redressability.
  - Check ripeness (not too early) and mootness (still a live dispute).
  - Avoid claims that seek advisory opinions.

- Pick the right forum and venue:
  - If filing in federal court, confirm the proper district and division.
  - Consider removal from state court if the case meets federal jurisdiction.

- Preserve the jury trial right in federal criminal cases:
  - Expect a jury unless strict waiver requirements are met.
  - Confirm venue in the state of the offense or as provided by statute if outside any state.

- Plan for appellate review:
  - Build a clear record and preserve objections to enable meaningful review.
  - Understand that the Supreme Court mostly reviews cases by writ of certiorari; original jurisdiction is very limited.

- Treason cases:
  - Note the narrow definition and strict proof requirements (two-witness rule or open-court confession).
  - Punishment is set by Congress, without penalties that affect descendants.

- Government actions and checks and balances:
  - Be prepared for judicial review of legislative and executive actions.
  - Agencies and officials may be required to follow constitutional and statutory limits.

- Teaching and study tips:
  - Learn the three sections’ text and themes.
  - Memorize the main jurisdiction categories and the jury trial guarantee.
  - Tie the concepts to cases like Marbury, Milligan, Brown, and Lujan.

## Summary Checklist

- Article III creates the Supreme Court and lets Congress establish lower courts.
- Federal judges serve during good behavior; pay cannot be reduced.
- Judicial power extends to defined categories, including federal questions and diversity.
- Supreme Court original jurisdiction is limited; most cases reach it by appeal.
- Federal criminal cases carry a jury-trial guarantee and venue rules.
- Treason is narrowly defined and requires two witnesses or open-court confession.
- Standing requires injury, causation, and redressability; no advisory opinions.
- Judicial review (Marbury) allows courts to set aside unconstitutional laws and actions.
- Eleventh Amendment limits suits against states by private parties.

## Quick Reference

| Concept                        | Source                              | Key Takeaway                                              |
| ------------------------------ | ----------------------------------- | --------------------------------------------------------- |
| Supreme Court created          | Article III, Section 1              | Congress sets lower courts; judges have life tenure       |
| Appellate vs original          | Article III, Section 2              | Original is limited; most cases reach the Court on appeal |
| Federal question cases         | Article III, Section 2; 28 USC 1331 | Federal courts interpret and apply federal law            |
| Standing (injury-cause-remedy) | Article III; Lujan (1992)           | Plaintiffs need a real, fixable injury                    |
| Jury trials in federal crimes  | Article III, Section 2; 6th Amend.  | Jury required; venue in state of the offense              |
| Treason definition and proof   | Article III, Section 3              | Narrow definition; two witnesses or open-court confession |


Article III of the U.S. Constitution: Courts, Jurisdiction, and Key Cases