Custom - has been defined as a rule of conduct formed by repetition of acts, uniformly observed (practiced) as a social rule, legally binding and obligatory (Sta. Maria) ; a general consistent practice of states followed by them from a sense of legal obligation, this statement contains the two basic elements of custom: the material factor, that is, how states behave and the psychological or subjective factor, that is, why they behave the way they do.

Opinio Juris Sive Necessitatis – Latin “Opinion that an act is necessary by rule of law” ; the principle that for conduct or practice to become a rule of customary international law, it must be show that nations believe that international law (rather than moral obligation) mandates the conduct or practice – also termed opinion juris

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.

Treaty – a compact made between two or more independent nations with a view to the public welfare; a treaty is not a law but also a contract between two nations and must, if possible, be so construed as to give full force and effects to all its parts.

General and Principles of Law – are mostly derived from the law of nature and are observed by the majority of the States because they are believed to be good and just. Although no international convention was necessary to bring them in to existence, the general principles of the law have nevertheless become universal in application because of the unilateral decision of a considerate number of States to adopt and observe them in recognition of their intrinsic merit

Municipal Law – that which pertains solely to the citizens and inhabitants of the state, and is thus distinguished from international law; in its more common and narrower connotation however it means those laws which pertains to towns, cities, and villages and their local government

International Law – those laws governing the legal relations between nations. Rules and principles of general application dealing with the conduct of nations and of international organizations and with their relations inter se, as well as with some of their relations with persons, whether natural or juridical

Courts – an organ of the government, belonging to the judicial department, whose function is the application of the laws to controversies brought before it and the public administration of justice. Simply, a body organized for the administration of justice.

Judicial Power – Judicial Power, according to Section of Article VIII of the Philippine Constitution, includes the duty of the courts of justice to settle actual controversies involving rights which are legally demandable and enforceable, and to determine whether there has been a grave abuse of discretion amounting to lack or excess of jurisdiction on the part of any branch or instrumentality of the government

Are the Decisions Law? Yes according to Article VIII of the New Civil Code of the Philippine Constitution “Judicial decisions applying or interpreting the laws of the Constitution shall form part of the legal system of the Philippines” However, only the decision of the Supreme Court are treated as such, the decisions of the lower courts have not in practice been considered as law because these cases are largely not reported or published

Dispositive Portion – that portion of the case where the order of the court is stated or the conclusion the case. In Philippine cases, it usually begins with the word “Wherefore”

Separate Opinions – the portion of the case where a member of the court would state his reasons and legal basis for not agreeing with the main opinion. Usually, stated after the main opinion

Obiter Dictum – Latin “Something said in passing” judicial comment made while delivering a judicial opinion, but one that is unnecessary to the decision in the case and therefore not prudential (although it may be considered persuasive) – Often shortened to Dictum or, less commonly Obiter dicta

- “Strictly speaking an ‘obiter dictum’ is a remark made or opinion expressed by a judge, in his decision upon a cause, ‘by the way’ – that is, incidentally or collaterally, and not directly upon the question before the court; or it is any statement of law enunciated by the judge or court merely by way of illustration, argument, analogy, or suggestion… In the common speech of lawyers, all such extrajudicial expressions of legal opinion are referred to as ‘dicta,’ or ‘obiter dicta,’ these two terms being used interchangeably.”

Leading Case – among the various cases that are argued and determined in the courts, some, from their important character, have demanded more than usual attention from the judges, and from this circumstance are frequently looked upon as having settled or determined the law upon all points involved in such cases, and as guides for subsequent decisions, and from the importance they thus acquire are familiarly termed as “leading cases”

Landmark Case – a case where the Supreme Court rendered a decision that significantly changes existing law

Landmark Decision – a decision of the Supreme Court that significantly changes existing law

Judges – an officer so named in his commission, who presides in some court; a public officer, appointed to preside and to administer law in a court of justice; the chief member of a court, and charge with the control of proceedings and the decision of questions of law or discretion; a public officer who, by virtue of his office, is clothed with judicial authority.

Lawyers – a person learned in law; as an attorney, counsel, or solicitor; a person licensed to practice law

Counsel – an attorney or counselor; advice and assistance given by one person to another in regard to a legal matter, proposed line of conduct, claim or contention

Attorney – Strictly, one who is designed to transact business for another

Prospectivity – as a general rule, laws are prospective in nature and not retroactive. The New Civil Code of the Philippines provides under Article 4: “Laws shall have no retroactive effect, unless the contrary is provided.”

Ex Post Facto Laws – laws which are retroactive in nature; Ex Post Facto laws are explicitly prohibited by the constitution under the Section 22 of the Bill of Rights which states that, “No ex post facto laws or bill of attainder shall be enacted”

The Following are Ex Post Facto Laws:1. Law which makes a crime punishable, when it was not punishable at the time it was

committed.2. Law which aggravates a crime or makes it greater or graver than when it was committed.3. Law which provides for greater punishment to a crime than that annexed to it at the time of

commission.4. Law which alters the legal rules on evidence, and receives less or different testimony than

the law required at the time of the commission of the offense in order to convict defendant.5. Assumes to regulate civil rights only but in effect imposes a penalty or deprivation of a right

which when done was lawful.6. Deprives a person accused of a crime of some lawful protection to which he has become

entitled, like double jeopardy, or amnesty.

Stare Decisis – Latin “to stand by things decided”; the doctrine that, when the court has once laid down a principle to a certain state of facts, it will adhere to that principle and apply it to all future cases where the facts are substantially the same, regardless of whether the parties and property are the same. Stare Decisis simply declares that, for the sake of certainty, a conclusion reached in one case should be applied to those which follow, if the facts are substantially the same, even though the parties may be different.

Res Judicata – This is the rule that a final judgment rendered by a court of competent jurisdiction on the merits is conclusive as to the rights of the parties and their privies, and, as to them, constitutes an absolute bar to a subsequent action involving the same claim, demand or cause of action. Simply a thing or matter settled by judgment or that has already been decided. Identity of parties, subject matter, cause of action

Law of the Case – Law of the case has been defined as the opinion delivered on a former appeal. It is a doctrine holding that a decision rendered in a former appeal of a case is binding in a latter appeal. The general rule is that legal conclusions announced on a first appeal, whether on the general law or the law as applied to the concrete facts, not only prescribed the duty and limit the power of the trial court to strict obedience and conformity thereto, but they become and remain the law of the case in all after steps below or above on subsequent appeal. The rule is ground on convenience, experience, and reason.

Courts of Equity – a court which has jurisdiction in equity, which administers justice and decides controversies in accordance with the rules, principles, and precedents of equity, and which follows the form and procedure of chancery; as distinguished from a court having the jurisdiction, rules, principles, and practice of law. In the Philippines, our courts are both courts of equity and courts of law.