The US Supreme Court has rejected an attempt to give residents of the territory of Puerto Rico the right to vote in US presidential elections.
Judges threw out the appeal by a group of Puerto Ricans - the latest development in a long-running debate on the islanders' constitutional rights.
Puerto Rico, which is not a state, has been administered by the US since 1898.
Although residents cannot vote in presidential elections, they do elect a delegate to the US Congress.
However their representative does not vote, except in committees.
Attorney Gregorio Igartua, who filed the appeal, said the citizens of Puerto Rico "have been unfairly treated" for more than a century.
He complained that residents have "an inferior type of American citizenship."
Correspondents say the argument about Puerto Rico's status is coming to a head following a report by the Bush administration into the issue.
In December, a presidential task force recommended that Congress call a referendum on the island's status as a self-governing US commonwealth.
A "Yes" vote would trigger another vote on whether to make Puerto Rico independent or the 51st US state.
Opinion polls suggest there is little support for independence. Only a few islanders voted in favour of independence in the latest of a series of referendums in 1998.
However, islanders are split over whether to keep their current status or become a US state.