Within the territorial bounds of the Philippines, it is the laws enacted by its own legislative body, interpreted and applied by its own Supreme Court, that primarily govern. This stems from the very nature of sovereignty and the inherent power of a state to dictate the rules within its domain. Our courts are, with the exception of the Supreme Court, creatures of Philippine statutes, their authority and jurisdiction defined by the very laws they are tasked to uphold.

However, the world has become increasingly interconnected, and transactions and relationships often transcend national borders. Recognizing this reality, and in adherence to the principles of international comity -- that courteous respect for the laws and judicial decisions of other nations, Philippine law acknowledges instances where foreign laws may be given effect within the Philippine territory, recognized by Philippine courts, and enforced by the Philippine legal system. This is not a derogation of sovereignty but a pragmatic approach to dealing with cross-border issues and fostering harmonious international relations. In a manner of speaking, when in Rome, the Greeks do as the Romans do but the expectation is that certain officials acts emanating from Greece will be given effect in Rome.

The three requisites of a successful conflicts case -- the presence of a foreign element, the referral by Philippine law to foreign law, and the proper pleading and proof of the foreign law -- form the bedrock of this exception. The "foreign element" signifies a factual connection to another jurisdiction, be it the nationality of a party, the place where a contract was executed, or the location of property. This connection triggers the potential application of choice-of-law rules within Philippine private international law.

The second requisite, the referral by relevant municipal law, is crucial. Philippine law itself must contain provisions that direct our courts to consider and apply the law of another jurisdiction in specific situations. These "choice-of-law rules" are embedded in our statutes and jurisprudence, guiding the local forum in determining which legal system should govern a dispute with foreign connections. For instance, Article 16 of the Civil Code states that intestate and testamentary succession, with respect to the order of succession, the amount of successional rights, and the intrinsic validity of testamentary provisions, shall be regulated by the national law of the person whose succession is under consideration, regardless of the nature of the property or the country wherein said property may be found. Here, Philippine law explicitly points to the application of a foreign national law in matters of succession involving a foreign national. This is known in textbooks as the principle of lex nationalii or the nationality principle.

The third requisite, the proper pleading and proof of the foreign law, underscores the procedural burden on the party seeking its application. Philippine courts operate based on Philippine law, and foreign law is treated as a question of fact that must be adequately pleaded, proved and offered in accordance with Philippine evidence law; secundum allegata et probata. This typically involves the submission of official publications of the foreign law, attested to by relevant authorities, and, in limited situations, the testimony of expert witnesses who can interpret and explain its provisions to the court. Without proper pleading and proof, the foreign law is presumed to be the same as Philippine law -- the principle of processual presumption.

There is a caveat, however, regarding public policy which is paramount in our jurisdiction. Even if all three requisites are met, Philippine courts will not apply a foreign law if doing so would violate the fundamental principles of justice, morality, good customs, or any other deeply rooted public policy of the Philippines, especially if the same arising from a categorical provision of the Constitution. This acts as a safeguard, ensuring that the application of foreign law does not undermine the core values of the forum state. For example, a foreign law that permits absolute divorce, while Philippine law does not for and between Filipino citizens, would likely be deemed contrary to Philippine public policy concerning the sanctity of marriage.

Suppose that a contract is entered into in Singapore between a Filipino corporation and a Singaporean company. The contract stipulates that it shall be governed by Singaporean law. If a dispute arises and is brought before a Philippine court, the case contains a foreign element (the Singaporean juridical entity and the place of execution). The express stipulation in the contract constitutes a referral by the parties, which Philippine courts generally recognize as a valid choice-of-law provision. However, the Singaporean law governing the specific issue in dispute must be properly pleaded and proved before the Philippine court. Even if these are satisfied, if a provision of the Singaporean law is found to be in direct contravention of a fundamental public policy of the Philippines, the Philippine court may refuse to apply that specific provision, applying instead the relevant Philippine law.

Another illustration can be drawn from family law. If a foreign national seeks to adopt a Filipino child in the Philippines, their national law regarding adoption will be given due consideration because our laws require reciprocity in treatment over the adopted between the national law of the adopters and our own. (See, for instance, Section 11 of the Inter-Country Adoption Act of 1995 [Republic Act No. 8043, June 07, 1995]) Similarly, in matters of marriage involving a foreign national, their national law regarding the capacity to marry will be relevant, again subject to proper proof as shown by Article 21 of the Family Code of the Philippines (Executive Order No. 209).

The truth is that there arises no "true" problem  if the laws of a foreign country are different from our laws because the function of private international law is not to determine the differences between the two. Rather, the goal is to determine which applies on a given set of facts with a foreign element. This only becomes an issue if the foreign law pleaded and proved contravenes our public policy.

The term “forum state” refers to the country in whose court the case is pending. The term “forum” refers to the court in whose dockets the case is pending.