Humberto Leal Garcia Jr., who was found guilty of raping and killing a 16-year-old girl in 1994, is scheduled to face lethal injection Thursday in Texas. Leal, now 38, was provided with court-appointed lawyers after his arrest but was never informed that he could have access to Mexican consular officials, as is required under the United Nations’ Vienna Convention on Consular Relations.

In 2009, the International Court of Justice ruled that the United States had failed to meet its obligations under the Vienna Convention in the cases of 51 Mexicans awaiting execution, including Leal.

The Obama administration urged the Supreme Court on Friday to delay the execution, saying that if it were carried out, it would affect “foreign-policy interests of the highest order.” The Mexican ambassador to the United States, Arturo Sarukhan, has also requested a reprieve for Leal based on concerns about legal representation.

The breach of international obligations would “have serious repercussions for United States foreign relations, law-enforcement and other cooperation with Mexico, and the ability of American citizens traveling abroad to have the benefits of consular assistance in the event of detention,” Solicitor General Donald B.Verrilli, Jr. wrote in an amicus brief filed with the court.

Despite the pleas, the Texas Board of Pardons and Paroles on Tuesday rejected Leal’s request for a delay.

Three years ago, Texas executed another Mexican national on death row despite international entreaties. Jose Ernesto Medellin, who also had not been informed of his right to access consular officials, was put to death following pleas for a stay by the Bush administration, which also cited U.S. treaty obligations.

In Leal’s case, even if the Supreme Court does not intervene, Texas Gov. Rick Perry could grant a 30-day stay.