WASHINGTON – Texas can ignore President Bush and an international court in refusing to reopen the case of a Mexican on death row for rape and murder, the Supreme Court said Tuesday.

The court said Bush exceeded his authority when he tried to intervene on behalf of Jose Ernesto Medellin, facing the death penalty for killing two teenagers nearly 15 years ago.

The Constitution “allows the president to execute the laws, not make them,” Chief Justice John Roberts wrote in a rebuke of the president in a case that mixed presidential power, international relations and the death penalty.

Justice Stephen Breyer, in dissent, said the decision calls into question U.S. obligations under international treaties and makes it “more difficult to negotiate new ones.”

By a 6-3 vote, the court said Texas does not have to give a new hearing to death row prisoner Jose Ernesto Medellin, a former Houston gang member who is now 33.

The president was in the unusual position of siding with 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.

Bush, who oversaw 152 executions as Texas governor, disagreed, but he said it must be carried out by state courts because the United States had agreed to abide by the world court’s rulings. The administration argued that the president’s declaration is reason enough for Texas to grant Medellin a new hearing.