WASHINGTON (CNN) -- A Mexican national on Texas' death row is awaiting possible last-minute intervention from the Supreme Court, just hours before he is scheduled to be put to death Tuesday for two brutal slayings. Jose Ernesto Medellin's execution by lethal injection could be the final act in an unusual capital appeal that pitted President Bush against his home state in a dispute over federal authority, local sovereignty and foreign treaties.
The high court in March ruled for Texas, allowing the execution to proceed, but Medellin's lawyers have filed a flurry of emergency appeals in state and federal courts requesting a stay.
They argue Congress and the Texas legislature should be given a chance to pass legislation that would give their client a new hearing before any punishment is carried out.
Such a bill is pending in Congress, but no recent action has been taken in either chamber.
In an August 1 letter, three Democrats on the House Judiciary Committee urged Texas Gov. Rick Perry to postpone upcoming executions "in order to provide Congress with the time needed to consider this situation."
Texas lawmakers will not gather in session until January.At issue is whether the state has to give in to the president's demand that the prisoner be allowed new hearings and sentencing.
Bush made that demand reluctantly after an international court concluded Medellin and about 50 other Mexicans on American death rows were improperly denied access to their consulate upon arrest, a violation of a treaty signed by the United States decades ago.
Medellin's execution would be the first of what promises to be a busy month at the state's death chamber in Huntsville. Five other men are scheduled to die by lethal injection in the next four weeks, including inmate Heliberto Chi Acheituno on Thursday.
Medellin was 18 when he took part in the June 1993 gang rape and murder of two Harris County girls, Jennifer Ertman, 14, and Elizabeth Pena, 16. He was convicted of the crimes and sentenced to death.
The prisoner's lawyers argued Mexican consular officials were not able to meet with the man until after his conviction.
Thirteen Texas death row inmates from Mexico will be affected by the high court ruling. Only Oklahoma has commuted a capital inmate's sentence to life in prison in response to the international judgment.
The International Court of Justice ruled in 2004 the United States had violated the rights of those prisoners, in part because officials and prosecutors failed to notify their home country, from which the men could have received legal and other assistance.
Those judges ordered the United States to provide "review and reconsideration" of the sentences and convictions of the Mexican prisoners.
That world court again last month ordered the United States to do everything within its federal authority to stop Medellin's execution until his case can be further reviewed.
Based in The Hague, Netherlands, the world court resolves disputes between nations over treaty obligations. The United States is one of the signatories to the 1963 Vienna Convention, laying out rights of people detained in other nations. The Supreme Court appeal turned on what role each branch of government plays to give force to international treaty obligations.
Chief Justice John G. Roberts wrote for a 6-3 majority that international court judgments cannot be forced upon individual states. The president also cannot "establish binding rules of decision that pre-empt contrary state law," he said, and the treaty itself does not specifically require states to remedy any treaty violations.
The 58-year-old chief justice added that the world court "is not domestic law," thereby restricting the president's power over states. "The executive's narrow and strictly limited authority to settle international claims disputes pursuant to an executive agreement cannot stretch so far as to support the current presidential memorandum" that would force Texas to conduct a new state trial, he wrote.
The Mexican government had filed an appeal with the International Court of Justice against the United States in January 2003, alleging violations of international law. Medellin filed his own federal and state appeals based on similar complaints, as well as a claim of ineffective counsel. Medellin has the support of the European Union and several international human rights groups.
Bush said he disagreed with the world court's conclusions but agreed to comply with them. In a February 28, 2005, executive order, he said, "The United States will discharge its international obligations ... by having state courts give effect to the decision in accordance with general principles of comity in cases filed by the 51 Mexican nationals addressed in that decision."
The Bush White House typically backs states in their power to carry out executions, but Justice Department officials said that in these instances, the president's power to conduct foreign policy outweighed states' interests.
The Supreme Court originally heard the Medellin case in 2005 but did not rule on its merits. It waited instead for lower courts to resolve the federalism angle before rehearing the appeal in October.