Judicial decisions—whether from international tribunals (e.g., ICJ) or domestic courts—are not formal sources of international law, but they are important persuasive authorities.

They help interpret, apply, and develop international law, especially where treaty text is vague or customary rules are evolving. In Philippine practice, the Supreme Court often draws from international rulings and comparative jurisprudence when resolving cases involving treaties, extradition, human rights, and state obligations.

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Medium–High yield in Public International Law and Political Law, commonly tested under sources of international law (Art. 38, ICJ Statute) and in problems where courts reconcile international obligations with constitutional rights. A common trap is treating judicial decisions as binding sources rather than interpretative guides.

Secretary of Justice v. Lantion, G.R. No. 139465, January 18, 2000 (Supreme Court; Lawphil).

The U.S. requested the extradition of Mark Jimenez under the RP–US Extradition Treaty. During the DOJ’s evaluation, the Secretary of Justice withheld the request and documents from Jimenez, claiming confidentiality.

The Supreme Court held that due process applies even at the evaluation stage of extradition because the process affects liberty. A prospective extraditee has the right to be informed and to access relevant documents to prepare a defense; withholding them violates due process.

🥜 Due process applies at all stages of extradition—liberty interests require notice and access to documents even during preliminary evaluation.