Legal Terminology

Why This Matters

Legal terminology isn't just vocabulary—it's the framework that determines how justice actually works. When you understand terms like jurisdiction, due process, and mens rea, you're learning the operating system of American courts. These concepts explain why cases end up in certain courts, how trials unfold, and what makes conduct legally punishable. Every term connects to bigger questions about fairness, constitutional rights, and the balance between individual liberty and social order.

You're being tested on more than definitions. Exam questions will ask you to apply these terms to scenarios, compare how different concepts interact, and explain why certain procedures exist. Don't just memorize that "habeas corpus" means something about detention—know that it's a constitutional safeguard against government overreach. The terms below are grouped by function so you can see how they work together in the legal system.

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Sources of Legal Authority

The law doesn't appear from nowhere—it comes from specific sources that courts must recognize and apply. Understanding where law originates helps you analyze why certain rules exist and how they can be challenged.

Statute

• Written law enacted by a legislative body—Congress, state legislatures, or local governments create these formal rules
• Provides specific, codified regulations that govern conduct and establish penalties for violations
• Can be challenged in court if deemed unconstitutional or improperly applied, making judicial review essential

Precedent

• Legal principle from previous cases that guides future court decisions—the foundation of stare decisis ("let the decision stand")
• Binding on lower courts within the same jurisdiction, creating consistency across similar cases
• Promotes predictability in law, allowing people to understand their rights and plan their conduct accordingly

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Court Authority and Structure

Before any case can proceed, courts must establish they have the power to hear it. Jurisdiction determines which court handles which disputes—get this wrong, and the entire case can be dismissed.

Jurisdiction

• Authority of a court to hear and decide a case—without it, any ruling is void
• Three main types: geographic (where events occurred), subject matter (type of case), and personal (power over the parties)
• Determines state vs. federal court based on factors like diversity of citizenship or federal questions

Certiorari

• Writ issued by a higher court to review a lower court's decision—literally means "to be made certain"
• Primary method the Supreme Court selects cases, granting "cert" to only about 1% of petitions
• Signals legal significance when granted, as the Court typically reviews cases involving constitutional questions or circuit splits

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Parties and Their Roles

Every case involves people or entities with specific legal designations. These labels determine who carries what burden and what rights each party possesses.

Plaintiff

• Party who initiates a lawsuit by filing a complaint—they're claiming they've been wronged
• Bears the burden of proof and must prove their case by a preponderance of the evidence in civil matters
• Seeks a legal remedy such as monetary damages, injunctions, or declaratory relief

Defendant

• Party being accused or sued—responds to the plaintiff's claims
• Constitutional right to defend against accusations, including presenting evidence and cross-examining witnesses
• Presumed innocent in criminal cases until proven guilty beyond a reasonable doubt

Amicus Curiae

• "Friend of the court" brief submitted by non-parties who have relevant expertise or interest
• Provides additional perspectives on complex legal or social issues the court may not have considered
• Common in landmark cases involving civil rights, constitutional interpretation, or significant public policy

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Criminal Law Foundations

Criminal law requires proving both a guilty act and a guilty mind. These Latin terms appear constantly on exams because they're the building blocks of criminal liability.

Mens Rea

• Mental state or intent when committing a crime—the "guilty mind" required for most criminal convictions
• Four levels recognized: purposely, knowingly, recklessly, and negligently—each affects charge severity
• Distinguishes accidents from crimes since most offenses require some degree of culpable mental state

Actus Reus

• Physical act constituting the offense—the "guilty act" that must accompany mens rea
• Can include omissions when there's a legal duty to act (parents failing to feed children, for example)
• Must be voluntary since involuntary movements or reflexes don't create criminal liability

Indictment

• Formal charge of a serious crime issued by a grand jury after reviewing prosecution evidence
• Required for federal felonies under the Fifth Amendment—initiates the formal prosecution process
• Grand jury decides probable cause, not guilt, using a lower standard than trial conviction

Arraignment

• Court proceeding where defendant enters a plea—guilty, not guilty, or no contest
• Occurs after indictment and formally begins the adversarial process
• Defendant informed of rights including right to counsel and the specific charges against them

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Civil Wrongs and Remedies

Not all legal wrongs are crimes. Civil law handles disputes between private parties, with different standards of proof and different types of relief.

Tort

• Civil wrong causing harm to another person—distinct from crimes, which are offenses against the state
• Creates legal liability requiring the wrongdoer to compensate the victim through damages
• Three main categories: negligence (carelessness), intentional torts (deliberate harm), and strict liability (liability without fault)

Injunction

• Court order requiring or prohibiting specific conduct—a form of equitable relief beyond money damages
• Can be temporary or permanent depending on the stage of litigation and nature of harm
• Prevents ongoing harm when monetary damages would be inadequate (like stopping environmental pollution)

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Constitutional Protections

These terms represent fundamental rights that limit government power. They're frequently tested because they connect legal procedure to constitutional principles.

Due Process

• Constitutional guarantee of fair proceedings—found in both the Fifth and Fourteenth Amendments
• Two types: procedural (fair procedures like notice and hearing) and substantive (protection of fundamental rights)
• Protects against arbitrary government action denying life, liberty, or property without proper legal safeguards

Habeas Corpus

• Protection against unlawful detention—literally "you shall have the body"
• Requires government to justify imprisonment before a judge, who determines if detention is legal
• Cannot be suspended except in rebellion or invasion, making it a cornerstone of liberty against executive overreach

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Pre-Trial Procedures

Most legal work happens before trial. These procedures gather evidence, select juries, and sometimes resolve cases entirely without going to court.

Subpoena

• Legal order to appear or produce evidence—compels cooperation in legal proceedings
• Failure to comply constitutes contempt and can result in fines or imprisonment
• Two types: subpoena ad testificandum (to testify) and subpoena duces tecum (to produce documents)

Deposition

• Sworn out-of-court testimony taken before trial—part of the discovery process
• Preserves testimony and allows both sides to learn what witnesses will say
• Can impeach witnesses if their trial testimony contradicts their deposition statements

Affidavit

• Written statement sworn under oath—signed before a notary or authorized official
• Used to support motions when live testimony isn't practical or necessary
• Carries legal consequences for false statements, including perjury charges

Voir Dire

• Jury selection process where attorneys question potential jurors—French for "to speak the truth"
• Identifies bias or conflicts that would prevent fair judgment
• Two challenge types: for cause (unlimited, based on demonstrated bias) and peremptory (limited, no reason required)

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Case Resolution

Not every case goes to trial. These mechanisms resolve disputes through negotiation or procedural shortcuts.

Plea Bargain

• Agreement between defendant and prosecutor where defendant pleads guilty to reduced charges
• Resolves approximately 90% of criminal cases in the United States, making it essential to the system's functioning
• Benefits both sides: defendant gets lighter sentence, prosecution avoids trial uncertainty and expense

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Quick Reference Table

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Self-Check Questions

1. Both mens rea and actus reus must be proven for criminal liability. Explain why proving only one element would be insufficient for a conviction.

2. Compare and contrast due process and habeas corpus. In what situations would a defendant invoke each protection?

3. Which terms describe the sources of legal rules that courts must follow? How do these sources interact when they conflict?

4. A witness gives testimony in a deposition that differs from their testimony at trial. What term describes using this inconsistency, and why is this procedure valuable?

5. If an FRQ presents a scenario where someone is detained without charges, which constitutional protection applies? Explain how this safeguard limits government power.