By Jonathan Beale
BBC state department correspondent, Washington
The US has withdrawn from part of an international agreement being used to fight for foreigners on death row.
Death row cases are causing tension between Mexico and the US
The Vienna Convention gave the International Court of Justice the right to intervene in the cases of foreigners held in US jails.
But the US state department says it is not appropriate that an international court should reverse the decisions of a country's criminal justice system.
The US was one of the original architects of the convention.
Part of the Vienna protocol requires that the ICJ makes a final decision when citizens of its signatory nations have been jailed abroad, specifically if they have been denied access to a diplomat from their own country.
The convention was seen as a means of protecting US citizens who had been jailed abroad, but in recent years the protocol has been used by opponents to the death penalty in the United States.
'Committed to obligations'
The US Supreme Court is set to consider arguments later this month in the case of a Mexican citizen on death row in Texas.
His lawyers are invoking the Vienna Convention to get his sentence overturned.
Some 51 Mexicans on death row in Texas have already been granted new hearings as a result of the intervention of the ICJ.
The issue has created tension between Mexico and the US and this announcement coincides with Secretary of State Condoleezza Rice's visit to Mexico for talks with President Vicente Fox.
A state department spokesman insisted that the US was still committed to its international obligations despite the withdrawal.
He said that most of the countries that had signed up to the ICJ had also not agreed to this part of the convention.