WASHINGTON, March 25 (UPI) -- The U.S. Supreme Court, in a rejection of World Court authority, ruled 6-3 Tuesday that a Mexican national cannot further appeal his Texas death sentence.

The decision also rejects the intent of a presidential memorandum.

The U.N. International Court of Justice, commonly called the World Court based at The Hague (OTCBB:HGUE), ruled in 2004 that Jose Medellin and 50 other Mexican nationals had been deprived of their rights under the Vienna Convention on Consular Relations. It said their U.S. sentences should be reviewed regardless of U.S. state law. Under the convention, foreign national suspects must be told they are entitled to a visit by their consuls.

But the U.S. Supreme Court later ruled that the convention did not pre-empt U.S. state law on appeals. In response, U.S. President George Bush issued a memorandum saying the United States would "discharge its international obligations ... by having state courts give effect to the (ICJ) decision."

Medellin, who was born in Mexico but lived most of his life in Houston, was facing a death sentence for the murder of two teenagers. After the president's memo, he filed a second constitutional appeal, which violated the limits placed on appeals by Texas law.

A Texas appeals court dismissed his case, and Tuesday, in a decision written by John Roberts' title='Chief Justice John Roberts' class='tpstyle'>Chief Justice John Roberts, the U.S. Supreme Court agreed that neither the ICJ ruling "nor the president's memorandum constitutes directly enforceable federal law that pre-empts state limitations on the filing of successive habeas petitions (requests for constitutional review)."

(No. 06–984, Medellin vs. Texas)