The study of private international law presents a unique challenge, particularly within the Philippine legal system. Unlike many areas of domestic law that are neatly codified within specific statutes, the rules and principles governing conflict of laws are dispersed across a variety of sources. They are not contained in a single, comprehensive code, as one might find with the Family Code, the New Civil Code, the Revised Penal Code, or the Revised Corporation Code. Instead, these rules are scattered throughout the 1987 Constitution, various statutes, codes, and, perhaps most significantly, a substantial body of jurisprudence. Often, they lie almost hidden within legal provisions, easily overlooked by those whose expertise does not specifically lie in this field.

This characteristic of Philippine private international law is well-illustrated by examining certain provisions within the country's legal framework. For instance, Article 17 of the New Civil Code states that the forms and solemnities of contracts, wills, and other public instruments are governed by the law of the place where they are executed. While this provision might initially appear to be a straightforward rule within the realm of persons and family relations, its significance as a conflicts rule becomes apparent later in a law student's academic journey, typically around their third year. It is then that they recognize that this article directs Philippine courts, or the "local forum," to apply a foreign law—specifically, the law of the place of the contract's execution—in determining the validity of the contract's form and solemnities.

To illustrate, consider a scenario where two Filipinos enter into a contract of sale for real property located in Thailand, executing the contract in Bangkok. Should a dispute regarding this contract arise and be brought before a Philippine court, the court would be obligated to apply Thai law to ascertain whether the formalities required for the contract's valid execution were duly observed. If Thai law mandates specific formalities or procedures that were not followed, the Philippine court might deem the contract invalid in terms of its form, even if Philippine law imposes different requirements for similar contracts executed within the Philippines.

Another example involves a Filipino citizen residing in California who executes a will there. Upon the testator's death and the subsequent probate proceedings in the Philippines, the Philippine court will refer to California law to determine if the will was executed with the necessary formalities, such as the number of witnesses, the testator's signature, and the attestation clause. If the will complies with California law regarding its form, it will generally be recognized as valid in that respect by the Philippine court, even if Philippine law prescribes different formalities for wills executed domestically. An exception to this rule is when the act is executed before Philippine diplomatic or consular officials in a foreign country. In such a case, Philippine law governs the formalities. For instance, if two Filipinos marry at the Philippine Embassy in Singapore, the solemnization of their marriage must adhere to the formal requirements of Philippine law, specifically the Family Code of the Philippines, despite the marriage ceremony taking place in Singapore.

Similarly, Article 146 of the Revised Corporation Code provides that a foreign corporation lawfully doing business in the Philippines is bound by all laws, rules, and regulations applicable to domestic corporations of the same class, except those concerning the creation, formation, organization, or dissolution of corporations, or those fixing the relations, liabilities, responsibilities, or duties of stockholders, members, or officers of corporations to each other or to the corporation. This provision embodies the "internal business rule," a principle in private international law. Initially, this provision might not strike one as a conflicts rule. However, upon closer examination, it becomes clear that it delineates the extent to which Philippine law applies to foreign corporations operating within the country.

For example, if a corporation incorporated in Delaware and licensed to do business in the Philippines breaches a contract with a Philippine company, a Philippine court would apply Philippine contract law to determine the foreign corporation's liability. This is because the contractual dealing is considered an external transaction subject to local law. Conversely, if a Filipino citizen purchases shares of stock in a Japanese corporation doing business in the Philippines and a dispute arises concerning the shareholder's rights vis-à-vis the Japanese corporation or its other shareholders (e.g., regarding voting rights, dividend declarations, or pre-emptive rights), a Philippine court would generally apply Japanese corporation law, the law of the place of incorporation, to resolve the matter, following the internal business rule. These issues pertain to the internal affairs of the foreign corporation and the relationships among the corporation and its stakeholders. Furthermore, the dissolution of the Japanese corporation would be governed by Japanese law, not Philippine law. The Philippines would recognize the dissolution if valid under Japanese law, and its license to do business in the Philippines may be terminated.

In essence, both Article 17 of the New Civil Code and Article 146 of the Revised Corporation Code function as "traffic rules," so to speak, within the Philippine legal system. They provide guidance to Philippine courts when confronted with situations involving a foreign element, directing them to consider and, in certain cases, apply foreign law. Without these rules, there would be significant uncertainty regarding which legal system should govern particular aspects of legal relationships or transactions that transcend national borders.