Private international law is so-called “private” because it involves the private
transactions of private individuals. It does not concern itself with the rights
and obligations of states and state actors but with contracts, relationships, or
obligations between private parties. On the other hand, the interaction between
states and state actors is the concern of public international law. It is part
of private law, not public law.While public law covers those fields such as criminal law that deals with crimes, private international law relates to contracts, succession, torts and other matters that do not involve the public at large or the government.
In order to grasp the foundational principle that distinguishes private international law from public international law, one must remember that the first deals with "private" transactions and relationships of individuals and entities, setting it apart from public international law's concern with the rights and obligations of states in the international community.
This designation of "private" is multifaceted, encompassing not only the nature of the parties involved but also the subject matter of the legal issues addressed.
Unlike public international law, which governs the interactions between sovereign states and international organizations, private international law delves into the realms of contracts, torts, family matters, property rights, inheritance, intellectual property, and commercial dealings – all areas traditionally considered within the sphere of private law. The central focus remains on the rights and obligations between these non-state or non-sovereign actors in situations that transcend national borders.
The very existence of private international law as a distinct field underscores the reality of a world comprised of numerous sovereign states, each possessing its own unique legal framework. This multiplicity of legal systems inevitably gives rise to situations where a legal issue contains a foreign element, thereby necessitating a set of rules to navigate these cross-border complexities. The core questions that private international law seeks to answer in such scenarios are threefold.
First, when a dispute arises, it becomes crucial to ascertain which court possesses the authority, or jurisdiction, to hear and adjudicate the case. Although the jurisdiction of courts or quasi-judicial agencies within one single system of law can be straightforward, in situations covered by private international law, there are rules to determine the appropriate forum -- between a local court or an alien forum -- for resolving cross-border legal conflicts.
Second, when parties from different jurisdictions engage in a legal relationship or dispute, the question arises as to which country's laws should govern that situation. This is the domain of choice of law, a process in the resolution of a conflicts case, where principles are established to determine the most appropriate legal system to apply.
Finally, once a judgment is rendered by a court in one country, the question of whether that judgment will be recognized and enforced in another jurisdiction becomes paramount. The principles governing the recognition and enforcement of foreign judgments are another vital component of private international law. Again, as to one single system of laws like the Philippines, there is little debate on how final and executory judgments are enforced against judgment debtors as already provided by existing rules such as Rule 39 of the Rules of Court.
While the distinction between private and public international law is generally well-defined, it is important to acknowledge certain nuances and areas where these two fields may intersect or influence one another. Although the primary actors in private international law are non-state entities, the role of the state is far from negligible. Domestic legal systems are the bedrock upon which private international law operates, as each country's laws contain the specific rules that their courts apply in cross-border cases. Furthermore, states actively engage in the harmonization of private international law rules through the negotiation and ratification of international treaties and conventions, such as the various Hague conventions addressing matters ranging from family law to commercial law.
In other words, if a question is asked as to the extent by which private international law is "international," the answer is mostly on details regarding the recognition and enforcement in another state of a judgment or judicial decree issued by a foreign court. Due to the equality of states, par in parem non habet imperium, there is a need to resort to principles governing public international law in the study of private international law.
Moreover, the concept of public policy, or ordre public, introduces an element where national public law considerations, especially if grounded on some fundamental considerations such as the provisions of a nation's constitution, can override the application of foreign private law as determined by choice-of-law rules. Domestic courts retain the prerogative to refuse the application of a foreign law if it is deemed to violate the fundamental principles of their own legal system. This acts as a safeguard, ensuring that the application of foreign law does not contravene deeply held national values.
Additionally, while distinct, private and public international laws can interact in specific contexts. For instance, international commercial arbitration, a prevalent method for resolving cross-border commercial disputes between private parties, is often shaped by international conventions and norms that fall within the ambit of public international law. In the Philippines, for example, this was touched upon in the case of Tuna Processing v. Philippine Kingford (G.R. No. 185582, February 29, 2012; 683 Phil. 276 [Second Division, Per J. Perez]). Similarly, issues concerning state-owned enterprises engaging in commercial activities with private entities might raise questions on state immunity, or the royal prerogative of dishonesty, which bridges both public and private international law considerations as exemplified in the case of Holy See v. Rosario (G.R. No. 101949, December 01, 1994; 308 Phil. 547 [En Banc, Per J. Quiason]).
An example of this would be a contract dispute between a Filipino corporation and a Japanese corporation. Private international law rules within the Philippines, or potentially in the other country or a third jurisdiction, would dictate which legal system governs the interpretation and enforcement of their agreement, depending on the situs of the court hearing the case. Similarly, if a Chinese tourist visiting Manila City were to cause an accident, the private international law rules of the Philippines would likely determine that Philippine tort laws apply to the issue of liability and damages.
In family law, should a couple residing in Pasay City but holding different non-Filipino citizenships decide to divorce, Philippine private international law would guide the determination of which country's divorce laws are applicable and whether the Philippine courts have the authority to hear the case. Even in matters of inheritance, if a foreign national owns property in Tuguegarao City upon their passing, Philippine private international law would likely dictate that the decedent's national law will govern as to the distribution of his property in the Philippines.