U.S. government lawyers asked the World Court, the top judicial branch of the United Nations, to reject Germany's demand for a legal sanction and reparations following the executions of two German citizens last year in Arizona.
The move came on the second day of hearings into the case of Walter and Karl LaGrand, put to death for the fatal stabbing of a bank manager near Tucson in 1982.
The case underscored the deep trans-Atlantic rift over capital punishment, which has been abolished throughout Europe. European countries protested in vain to delay a death sentence carried out Friday against a Mexican-born man who murdered a college student in Texas.
James Thessin, the chief U.S. agent to the court, admitted that Arizona authorities violated the Vienna Convention on Consular Relations by failing to inform the LaGrands upon arrest on Jan. 7, 1982, of their right to assistance from the German consulate.
He told the 15 justices that the United States has presented a formal apology to the German government.
Nevertheless, Thessin questioned Germany's motives in bringing the case to the international court, suggesting it was a ruse to put the U.S. justice system on trial and "litigate the death penalty under the guise of a violation to that convention."
International law, said Thessin, a State Department legal adviser, permits capital punishment "in accordance with due process of the law and stringent procedural safeguards, as is the case in the United States."
The U.S. agent maintained that the panel's jurisdiction is limited to interpretation of international treaties and does not have the power to review criminal procedures.
"Germany, in effect, has invited this court to create a new international legal obligation, one that would necessarily intrude deep into the domestic criminal justice system of any state," Thessin said.
Arizona Attorney General Janet Napolitano also apologized for the violation of the convention in the Lagrands' detention.
However, she rejected Germany's claims that consular officials could have provided mitigating evidence on their troubled childhood in Germany before they came to America with their German mother and stepfather, a U.S. serviceman.
The attorney general noted that they were born out of wedlock, suffered parental neglect, spent long periods in foster care and were discriminated against because of their mixed-race background.
Nevertheless, she reminded the court of the gravity of the crime. Frustrated by the failure of their robbery attempt, the LaGrands stabbed 63-year-old Kenneth Hartsock 24 times with a letter opener until he died and wounded a teller who lived to testify, Napolitano said.
Germany opened its case Monday by denouncing the death penalty and noting its cncern that dozens of foreigners now on death row may not have received proper consular representation.
German agent Gerhard Westdickenberg said violations of the Vienna convention continue despite U.S. promises to improve compliance.