Is their an obligatory rule that requires the Philippines to recognize foreign judgments? or allow a procedure for the enforcement thereof?

There is no obligatory rule derived from treaties or conventions that requires the Philippines to recognize foreign judgments, or allow a procedure for the enforcement thereof. However, generally accepted principles of international law, by virtue of the incorporation clause of the Constitution, form part of the laws of the land even if they do not derive from treaty obligations.^[66] The classical formulation in international law sees those customary rules accepted as binding result from the combination two elements: the established, widespread, and consistent practice on the part of States; and a psychological element known as the opinion juris sive necessitates (opinion as to law or necessity). Implicit in the latter element is a belief that the practice in question is rendered obligatory by the existence of a rule of law requiring it.^[67]

While the definite conceptual parameters of the recognition and enforcement of foreign judgments have not been authoritatively established, the Court can assert with certainty that such an undertaking is among those generally accepted principles of international law.^[68] As earlier demonstrated, there is a widespread practice among states accepting in principle the need for such recognition and enforcement, albeit subject to limitations of varying degrees. The fact that there is no binding universal treaty governing the practice is not indicative of a widespread rejection of the principle, but only a disagreement as to the imposable specific rules governing the procedure for recognition and enforcement.