Gera Tools

Legal Latin Terms Reference

Common Latin legal terms with plain-English definitions

Searchable glossary of Latin legal terms and maxims used in common and civil law, with plain-English definitions and area-of-law tags. Covers actus reus, habeas corpus, prima facie, stare decisis and more. It runs free in your browser on Gera Tools, with nothing uploaded.

Last updated Source: Gera Tools

Latin pervades legal language because both the civil-law tradition (descended from Roman law) and English common law preserved Latin terms and maxims for centuries. Understanding them is essential when reading judgments, statutes and pleadings. This tool is a searchable glossary: filter by keyword or by area of law to find the plain-English meaning of common terms.

How it works

Each entry pairs a Latin term or maxim with a concise modern definition and an area-of-law tag (criminal, procedure, contract, tort, evidence, constitutional or general). The search matches both the Latin and the English meaning, so you can look up mens rea directly or search “guilty mind” and find it. The area filter narrows the list — for example selecting “Criminal” surfaces actus reus, mens rea and nolo contendere, while “Procedure” surfaces ex parte, res judicata and subpoena.

Key terms by area of law

Criminal law

  • Actus reus — the physical act element of a crime (literally “guilty act”). Without it, no crime exists regardless of intent.
  • Mens rea — the mental element or guilty mind. Most serious offences require both actus reus and mens rea.
  • Nolo contendere — “I do not contest it.” A plea that accepts punishment without admitting guilt, used in US criminal procedure.
  • In flagrante delicto — caught in the act of committing an offence.

Procedure and courts

  • Ex parte — a hearing or order involving only one side, without notice to the other.
  • Res judicata — “the matter has been decided.” Prevents re-litigating a matter already settled by a final judgment.
  • Habeas corpus — “you shall have the body.” A writ requiring a court to examine the lawfulness of a detention.
  • Subpoena — a court order requiring a person to give testimony or produce documents.
  • Amicus curiae — “friend of the court.” A person or organisation permitted to advise the court on a matter it has an interest in.

Evidence and proof

  • Prima facie — “at first sight.” Evidence sufficient to establish a fact unless rebutted.
  • Res ipsa loquitur — “the thing speaks for itself.” Allows negligence to be inferred from the nature of the accident without direct evidence.
  • Alibi — literally “elsewhere.” The defence that the accused was in a different location when the offence occurred.

Case analysis

  • Ratio decidendi — the binding legal reason for a court’s decision; the part of a judgment that sets precedent.
  • Obiter dictum (plural: obiter dicta) — remarks made in passing, not essential to the decision and not binding as precedent.
  • Stare decisis — “to stand by things decided.” The doctrine of binding precedent: lower courts must follow the ratio of higher courts.

Natural justice

  • Audi alteram partem — “hear the other side.” No decision may be made without giving both parties a fair opportunity to be heard.
  • Nemo judex in causa sua — no one may judge their own case. Together with audi alteram partem, this forms the bedrock of procedural fairness.

Tips for reading judgments

  • Terms are conventionally italicised when used in English legal writing.
  • Ratio decidendi versus obiter dictum is one of the most examined distinctions in law. The ratio is binding on lower courts; obiter remarks are persuasive at most.
  • Civil-law and common-law systems share many Latin terms but sometimes use them differently. Where jurisdictional variation matters, verify the meaning in the applicable legal system.
  • This glossary is for general reference and is not legal advice.