Washington ? By his own admission, the crime was savage. Jose Medellin and five other gang members were drinking, brawling, swaggering, talking smack and hanging out by the railroad tracks near a Houston apartment complex on a warm night in June 1993. Along came two girls, Jennifer Ertman, 14, and Elizabeth Pena, 16, taking a shortcut home from a friend’s house.

Medellin stopped Pena. When she tried to run, he threw her to the ground. Ertman ran to help her but also was shoved to the ground. They were gang-raped and beaten.

Even as the girls begged for their lives, they were dragged to nearby woods and strangled, one with her own shoelace, the other with a belt and then by a shoe pressed on her windpipe. Their bodies were found four days later.

Medellin had no regrets. He bragged about the crime to his cousin and gave one of the girl’s rings to his girlfriend. His brother kept Ertman’s Disney-brand Goofy watch as a trophy.

It didn’t take long for police to catch Medellin. Once they did, he confessed. Nor did it take long for the jury to return a verdict: Guilty. And Texas-style justice means death for a crime like his.

For the past 13 years, Medellin has been on Death Row in Texas. Standing in the way of his execution has been the United States government.

Texas has taken the U.S. to court to allow it to execute Medellin. This week the case will be argued before the U.S. Supreme Court.

“It’s a crime even among capital crimes that stands out for its gruesomeness and its barbarity,” said R. Ted Cruz, the Texas solicitor general.

The case might be the ultimate test of states’ rights versus the power of the federal government.

Indeed, 28 states have signed on in support of Texas. But it also indicates the extent to which states are bound by international law and the United States’ treaty obligations.

The government of Mexico forced the U.S. stance. After Medellin was convicted, Mexico brought suit in the International Court of Justice, the judicial body of the United Nations, charging that the U.S. had violated the Vienna Convention.

That treaty requires that foreign nationals arrested in a signatory country be allowed to meet with a consular official from their home country.

It’s a tool treasured by diplomats worldwide. The U.S. once brought an action in the same court against Iran after the U.S. Embassy in Tehran was seized in 1979.

Although he had lived most of his life in Houston, Medellin was born in Mexico. Its government, like many in the world, is critical of capital punishment in the United States.

Mexico claimed that Medellin and 50 other Mexican nationals on Death Row in the U.S. had been denied their right to consult with its consulate, where they would have received legal assistance in an effort to avoid a death sentence.

The international court found for Mexico in 2004 and ordered the U.S. to review the convictions and death sentences of the 51 Mexican nationals.

“It’s the first time in the history of this nation that any foreign tribunal has asserted its authority to command the U.S. justice system,” Cruz said.

The White House criticized the ruling, but in 2005 it startled Texas officials and others by saying it would comply.

President Bush ordered the Texas courts to allow Medellin’s habeas corpus claim challenging his conviction to go forward, and Mexico praised the decision.

New York lawyer Donald Francis Donovan, who will argue on behalf of Medellin at the Supreme Court, said the case is about showing the international community that the U.S. lives up to its treaty obligations.

“What’s at stake is the U.S. commitment to the rule of law,” he said.