FOUNDATION: Unit V. International Human Rights in the Domestic US Context 6 of 7

Customary International Law (CIL) as Part of US Law

Joelito Filártiga, circa 1976

The US Constitution has provisions that deal with treaties, but there is no comparable provision dealing with customary international law (CIL). There are court cases based on CIL, but many questions remain about the relationship of CIL to law in the US.

For more information, click here: CIL.

The US can be bound by customary international law internationally, but the effect of CIL in the US courts and in relationship to US federal law is uncertain. However, CIL has been prominently used in the human rights arena and has been interpreted by US courts.

There hasn’t been a definitive ruling on the status of CIL in the US legal system, but two important cases imply that CIL is on equal footing with US federal common law. That means that CIL is slightly less important than treaty law or federal statutory law, but is still superior to state and local law.

1. The Paquette Habana Case
This was the first US case that helped establish the importance of customary international law.

2. The Filártiga v. Peña-Irala Case
The second case was more recent. In 1980, the Filártiga v. Peña-Irala case brought CIL into US courts to resolve a human rights issue: torture.  Joelito Filártiga had been abducted, tortured, and murdered by the police in Paraguay in 1976. His father, Joel Filártiga, took Joelito’s sister to the US seeking political asylum. The Filártigas learned that the police officer responsible for Joelito’s death, Norbert Peña-Irala, had also entered the US. The family decided to sue Peña in the US courts for the torture and wrongful death of Joelito. The US court got jurisdiction in this international case partly through the Alien Tort Statute, a federal law passed in 1789 that said aliens can file civil suits in US courts for torts that are also violations of international law. At that time, the US wasn’t party to the UN Convention Against Torture. But the lawyers for the Filártigas used customary international law to prove that torture was prohibited by the law of nations in the US. The case showed that US courts can consider CIL in their rulings. But the status of CIL in the US legal system remains unsettled and hotly debated.

What types of customary international law do you think should be incorporated automatically into US law?
Breaking Silence: The Case that Changed Human Rights
PBS: Trial History—Filártiga v. Peña-Irala