These two cases involve an Eighth Amendment challenge to juvenile sentences of life without parole. Taking no position on the constitutionality (or wisdom) of this type of sentence, Cato joined the Solidarity Center for Law and Justice, the Sovereignty Network, and 10 other groups to urge the Supreme Court not to consider non‐binding provisions of international human rights treaties and customary international law in its analysis. Our brief argues that the Court should leave to the political branches the decision of whether to transform international norms into domestic law and only allow duly ratified international agreements to override domestic law — in the way the Court has set out in cases such as Medellin v. Texas. It further contends that if the Court believes this is one of the rare cases where international norms are relevant, it should follow the test it laid out in Sosa v. Alvarez Machain, which addressed the (unrelated) Alien Tort Statute: The relevant norm must be widely accepted by the civilized world and as clearly defined as the historic “law of nations” norms regarding safe conduct permits, ambassadorial rights, and piracy on the high seas. The brief also cautions that reliance on non‐binding and indefinite international norms will undermine the democratic process and rule of law, casting considerable uncertainty over many U.S. laws.