Definitions are from Black's Law Dictionary (10th ed.)
actus reus [Law Latin "guilty act"] The wrongful deed that comprises the physical components of a crime and that generally must be coupled with mens rea to establish criminal liability; a forbidden act <the actus reus for theft is the taking of or unlawful control over property without the owner's consent>.
affirmative defense A defendant's assertion of facts and arguments that, if true, will defeat the plaintiff's or prosecution's claim even if all the allegations in the complaint are true. • The defendant bears the burden of proving an affirmative defense. Examples of affirmative defenses are duress (in a civil case) and insanity and self-defense (in a criminal case).
a fortiori [Latin] By even greater force of logic; even more so it follows <if a 14-year-old child cannot sign a binding contract, then, a fortiori a 13-year-old cannot>.
Alien Tort Claims Act A section in the Judiciary Act of 1789 giving federal courts jurisdiction to hear tort claims brought by foreigners who allege a violation of international law or a treaty to which the United States is a party. 28 USCA § 1350. • The statute was largely dormant until the 1980s, when it was invoked in several cases involving torture, disappearances, or killings committed by non-Americans in foreign countries. Later, alien plaintiffs began using the law to sue large corporations and the United States government or those acting at the government's direction. — Abbr. ATCA. — Also termed Alien Tort Statute.
amicus curiae [Latin "friend of the court"] Someone who is not a party to a lawsuit but who petitions the court or is requested by the court to file a brief in the action because that person has a strong interest in the subject matter. — Often shortened to amicus. — Also termed friend of the court. Pl. amici curiae.
certiorari [Law Latin "to be more fully informed"] An extraordinary writ issued by an appellate court, at its discretion, directing a lower court to deliver the record in the case for review. • The writ evolved from one of the prerogative writs of the English Court of King's Bench, and in the United States it beame a general appellate remedy. The U.S. Supreme Court uses certiorari to review most of the cases that it decides to hear. — Abbr. cert. — Also termed writ of certiorari.
continental shelf The submerged border of a continent where the seabed constitutes a relatively shallow landmass, usu. sloping gradually to a point of steeper descent, extending beyond a state's territorial sea through the natural prolongation of its land teritory to the outer edge of the submerged continental margin, or 200 nautical miles from the baselines from which the breadth of the territorial sea is measured, whichever distance is greater.
contra legem [Latin] Contrary to law; against the law.
de minimis non curat lex The law does not notice or concern itself with trifling matters.
dolus [Latin "device; artifice"] 1. Conduct intended to deceive someone; bad faith. • Although there may be dolus without fraud, fraud always includes dolus. 2. Intentional aggression; willful injury, esp. to another's property.
dolus directus [Latin] Foresight of and direct desire to produce the primary or direct consequences of an action.
dolus eventualis [Latin] Awareness of the probable outcome of an action.
dolus specialis [Latin] Special deceit.
erga omnes [Latin] Toward all.
estoppel 1. A bar that prevents one from asserting a claim or right that contradicts what one has said or done before or what has been legally established as true. 2. A bar that prevents the relitigation of issues.
ex hypothesi [Latin] Hypothetically; by hypothesis; on the assumption <conviction for a felony is ex hypothesi impossible in the case of suicide>.
ex injuria jus non oritur A right does not arise from wrongdoing. [Listed in Black's as ex iniuria ius non oritur.]
freedom of the seas The principle that the seas beyond territorial waters are not subject to any country's control. • Ships on the high seas are subject only to the jurisdiction of the country whose flag they fly, except in cases of piracy, hijacking, hot pursuit from territorial waters, slave trading, and certain rights of approach by warships. — Also termed mare liberum
inter alia [Latin] Among other things.
International Law Commission A body created in 1947 by the United Nations for the purpose of encouraging the progressive development and codification of international law. • The Commission is composed of experts in international law. It has drafted many important treaties that have become binding treaty law, including the Vienna Convention on the Law on Treaties. — Abbr. ILC.
juri gestionis [Latin "by way of doing business"] A country's acts that are essentially commercial or private, in contrast to its public or governmental acts. • Under the Foreign Sovereign Immunities Act, a foreign country's immunity is limited to claims involving its public acts. The statutory immunity does not extend to claims arising from the private or commercial acts of a foreign state.
juri imperii [Latin "by right of sovereignty"] The public acts that a country undertakes as a sovereign state, for which the sovereign is usu. immune from suit or liability in a foreign country.
jus ad bellum [Latin "right to war"] Criteria to be considered before deciding whether engaging in a war is just.
jus in bello [Latin "law in waging war"] The criteria for determining whether the conduct of an ongoing war is just.
jus cogens [Latin "compelling law"] A mandatory or peremptory norm of general international law accepted and recognized by the international community as a norm from which no derogation is permitted.
jus dispositivum [Latin "law subject to the disposition of the parties"] A norm that is created by the consent of participating countries, as by an international agreement, and is binding only on the countries that agree to be bound by it.
legal positivism The theory that legal rules are valid only because they are enacted by an existing political authority or accepted as binding in a given society, not because they are grounded in morality or in natural law.
lex ferenda [Latin] Law proposed for enactment.
lex lata [Latin] The law as it exists; enacted law.
male captus, bene detentus Wrongly captured, well detained.
mens rea [Law Latin "guilty mind"] The state of mind that the prosecution, to secure a conviction, must prove that a defendant had when committing a crime <the mens rea for theft is the intent to deprive the rightful owner of the property>. • Mens rea is the second of two essential elements of every crime at common law, the other being the actus reus.
mutatis mutandis [Latin] All necessary changes having been made; with the necessary changes <what was said regarding the first contract applies mutatis mutandis to all later ones>.
ne bis in idem [Latin] Scots law. Not twice for the same thing. • The phrase usu. referred to the law forbidding more than one trial for the same offense. It essentially refers to the double-jeopardy bar.
nulla peona sine lege [Latin] No punishment without a law authorizing it.
nullum crimen sine lege [Latin] No crime without law.
opinio juris (sive necessitatis) [Latin "opinion that an act is necessary by rule of law"] The principle that for conduct or a practice to become a rule of customary international law, it must be shown that countries believe that international law (rather than moral obligation) mandates the conduct or practice.
pacta sunt servanda [Latin "agreements must be kept"] Treaties (agreements) are to be observed.
pari passu [Latin "by equal step"] Proportionally; at an equal pace; without preference <creditors of a bankrupt estate will receive distributions pari passu>.
political question A question that a court will not consider because it involves the exercise of discretionary power by the executive or legislative branch of government. — Also termed nonjusticiable question.
political-question doctrine The judicial principle that a court should refuse to decide an issue involving the exercise of discretionary power by the executive or legislative branch of government.
post hoc 1. adv. After this; subsequently. 2. adj. Of, relating to, or involving the fallacy of assuming causality from temporal sequence; confusing sequence with consequence.
precautionary principle The doctrine that when there are threats of serious or irreversible damage to the environment, a lack of full scientific certainty is not a reason for postponing measures to prevent the damage.
ratione materiae By reason of the matter involved.
ratione personae By reason of the person concerned.
rebus sic stantibus [Latin "matters so standing"] The principle that all agreements are concluded with the implied condition that they are binding only long as there are no major changes in the circumstances.
reductio ad absurdum [Latin "reduction to the absurd"] In logic, disproof of an argument by showing that it leads to a ridiculous conclusion.
res judicata [Latin "a thing adjudicated"] An issue that has been definitively settled by judicial decision.
restrictive principle of sovereign immunity The doctrine by which a foreign country's immunity does not apply to claims arising from the country's private or commercial acts, but protects the country only from claims arising from its public functions.
self-executing (Of an instrument) effective immediately without the need of any type of implementing action <the wills had self-executing affidavits attached> • Legal instruments may be self-executing according to various standards. For example, treaties are self-executing under the Supremacy Clause of the U.S. Constitution (art VI, § 2) if textually capable of judicial enforcement and intended to be enforced in that manner.
stare decisis [Latin "to stand by things decided"] The doctrine of precedent, under which a court must follow earlier judicial decisions when the same points arise again in litigation.
sui generis [Latin "of its own kind"] Of its own kind or class; unique or peculiar.
tort A civil wrong, other than breach of contract, for which a remedy may be obtained, usu. in the form of damages; a breach of a duty that the law imposes on persons who stand in a particular relation to one another. • Tortious conduct is typically one of four types: (1) a culpable or intentional act resulting in harm; (2) an act involving culpable and unlawful conduct causing unintentional harm; (3) a culpable act of inadvertence involving an unreasonable risk of harm; and (4) a nonculpable act resulting in accidental harm for which, because of the hazards involved, the law imposes strict or absolute liability despite the absence of fault.
travaux préparatoires [French "preparatory works"] Materials used in preparing the ultimate form of an agreement or statute, and esp. of an international treaty; the draft or legislative history of a treaty.
ultra vires [Latin "beyond the powers (of)"] Unauthorized; beyond the scope of power allowed or granted by a corporate charter or by law <the officer was liable for the firm's ultra vires actions>.
uti possidetis The doctrine that the administrative boundaries will become international boundaries when a political subdivision or colony achieves independence.