WASHINGTON - President Bush overstepped his authority when he ordered a Texas court to grant a new hearing to a Mexican on death row for rape and murder, the Supreme Court said Tuesday.

In a case that mixes presidential power, international relations and the death penalty, the court sided with Texas 6-3.

Bush was in the unusual position of siding with death row prisoner Jose Ernesto Medellin, a Mexican citizen whom police prevented from consulting with Mexican diplomats, as provided by international treaty.

An international court ruled in 2004 that the convictions of Medellin and 50 other Mexicans on death row around the United States violated the 1963 Vienna Convention, which provides that people arrested abroad should have access to their home country's consular officials. The International Court of Justice, also known as the world court, said the Mexican prisoners should have new court hearings to determine whether the violation affected their cases.