Diplomatic asylum, understood as a particular form of sheltering fugitives, may be seen as the correlative to extradition, the mainly executive but also partly judicial process whereby an escapee is denied asylum (whether territorial or extraterritorial) and surrendered by one sovereign power to another for trial and punishment of criminal offenses. The usual protections for political offenders have been part of the custom and treaty law governing such rendition since the 1830s, the pioneering work of French, Belgian, and Dutch jurisconsults and legislators who reversed the pre-French Revolution tradition of surrendering political opponents and harboring ordinary criminals. In the United States, the paradigmatic act of 1848, "for the apprehension and delivering up of certain offenders," limited U.S. extradition practice not by category of alleged offense but through reciprocal international treaty. (The United States in 2001 had extradition treaties with more than one hundred other states.) As for multilateral extradition treaties, once again the republics of the Western Hemisphere led the way, beginning with the somewhat abortive treaties of 1889 and 1902, the distant precursors of the 1981 Inter-American Convention on Extradition, which explicitly protects "the right of asylum when its exercise is appropriate." There the burden of the proviso is to protect "political" fugitives specifically, though not exclusively. But, as the U.S. Departments of Justice and State both glossed apropos a typical extradition treaty with Jordan, "political offense" is a category frequently used but never defined in such treaties.
Until the post–World War II period the most controversial example of the political exemption for asylum-seekers was the refusal of the Dutch authorities to surrender Wilhelm II of Hohenzollern to the victorious Allies for trial as a war criminal under the terms of the Treaty of Versailles (article 227), which had arraigned the former kaiser for his "supreme offence against international morality and the sanctity of treaties." Since World War II and particularly the establishment of the ad hoc Nuremberg and Tokyo International Military Tribunals for the trial of war criminals (1945–1948), various multilateral instruments have diminished such residual protections, allusively so in the exhortatory Universal Declaration of Human Rights and specifically in the Convention on the Prevention and Punishment of the Crime of Genocide, both adopted by the UN General Assembly in December 1948. Controversies that have remained have usually been not for substantive reasons but rather on procedural grounds, for example grants of domestic immunity, the forceful seizure (kidnapping) of the accused, and unfitness to plead, the latter being argued in the high-profile case in 1998–2000 of the former president of Chile, General Augusto Pinochet, whose case was taken on appeal against extradition to the highest court in England, the House of Lords. (In this instance the executive rather than the judicial branch—an uncertain distinction in the British constitutional system—released Pinochet from extradition to Spain.)
Here again, American and European attitudes have been similar: "forcible abduction" is permissible, provided the terms of any extradition treaty are applicable; such was the decision in United States v. Verdugo-Urquidez (1992). Undoubtedly the most famous modern case in which kidnapping was ruled to be inconsequential to the prosecution of inter alia "war crimes" and "crimes against humanity" was that of the German Nazi leader Adolf Eichmann, which was decided on appeal before the Israeli Supreme Court in 1962. In this case the judges, as they put it, "rel[ied] on a long array of local, British, American and Continental precedents" to deny the appellant "asylum" in his former refuge of Argentina.
In the federal system of the United States extradition between states rests upon article 4, section 2, of the Constitution, requiring that "A Person charged in any State with Treason, Felony, or other Crime … shall … be delivered up" on demand by the applicant state. Significantly, the following paragraph implicitly invalidates the competence of any state to offer asylum and hence possible freedom to a fugitive slave—an interpretation borne out by the provisions of the contemporaneous Northwest Ordinance. (Congress passed a combined fugitive slave and extradition act in 1793.) This conjunction of principles in the federal Constitution acts as a valuable reminder of the intimate relationship between law and politics in American history, the permeability of the socalled domestic and foreign spheres, and that general and particularly universal statements of rights—what we would today call "human rights"—must always be seen in their historical and specific context. The defense of slavery by the signatories of the Declaration of Independence is the locus classicus of this discordant interplay, and the invocation of this same Declaration by the delegates to the Convention of Seneca Falls in 1848 likewise confirms the general rule, with this latter meeting on American women's rights itself deriving from the worldwide antislavery campaign.
Slavery and particularly the slave trade were a constant irritant in Anglo-American relations from Jay's Treaty of 1794 (which provided for limited extradition for certain felonies—hence conditional denial of "asylum"—between the two countries) through the War of 1812 and the abolition of slavery within the British empire in 1833 until the time of the Civil War. In the case of the slave mutiny upon the brig Creole in 1841, law officers in England ruled that the colonial authorities in the West Indies could not surrender the fugitives to the U.S. government without specific parliamentary approval. (There was also the separate though weighty matter of the slaves' gaining freedom by virtue of their arrival within the jurisdiction of the English courts—an issue that had pre-independence roots in the ground-breaking Sommersett case of 1772.) Extradition, in other words, though an executive function of government, required in this case statutory authority—a process of legitimation that came most notably through the first (British) Extradition Act of 1870, with its protections for political refugees.
The negotiation of the Webster-Ashburton Treaty of 1842 between Britain and the United States helped to resolve the legacy of the Creole dispute while agreeing on the terms of nonpolitical extradition. But the difficulties between American and British jurisdictions and jurisprudence over the definition of political as distinct from criminal ("terrorist") offenses reemerged with the resumption of the Irish Troubles in the late 1960s. Yet the two countries are not unique in their differences. As Guy Goodwin-Gill authoritatively observed: "International law provides no guidance on the substance of the concept [political offence exception], other than its outermost limits." Inside the United States, the early federal legislation on interstate rendition was interpreted by the U.S. Supreme Court in Kentucky v. Dennison (1861) as merely declaratory and thus discretionary. It remained until long after the abolition of slavery for the Supreme Court ( Puerto Rico v. Branstad, 1987) to rule that state authorities had no discretion on rendition. Interstate asylum, in other words, did not exist.