The 1st U.S. Circuit Court of Appeals declined to order Puerto Rico to restore to the electoral rolls some 330,000 people who were disqualified because they didn't cast ballots in 2008.
A three-judge panel in Boston voted 2-1 to uphold a district court's decision to deny the request for a preliminary injunction that would have enabled those voters to take part in Puerto Rico's Nov. 6 gubernatorial election.
The majority on the appellate panel concluded it would be impractical to grant the injunction with less than a month to go before the voting.
Puerto Rican law establishes that a citizen who does not vote in one election is eliminated from the list of individuals eligible to vote in the next, a provision that clashes with U.S. federal legislation.
Citing federal law, Puerto Rico's main opposition Democratic Popular Party, or PPD, sought in the courts over the past few weeks the reinstatement of those 330,000 excluded voters.
The Boston court's decision was taken after federal Judge Carmen Consuelo Vargas, who presided over a hearing of the case in San Juan, recommended Wednesday that the 330,000 struck from the rolls be allowed to vote.
Gov. Luis Fortuño, who is seeking a second four-year term, seemed concerned Thursday at the decision of the 1st Circuit about the matter, warning that trust in the electoral process itself was at stake.
Puerto Rico's top electoral official, Hector Conty, also warned that the logistical problems created by reinstating the 330,000 excluded voters, arguing that company in charge of the process did not have enough paper to print the necessary ballots.
The total number of eligible voters for Nov. 6 has increased to 2.4 million, according to Conty's office.
Puerto Ricans will go to the polls to elect the governor, the island's official representative at the U.S. Congress, legislators and mayors.
The Fortuño administration has also called for a non-binding referendum in which he will ask Puerto Ricans if they want to maintain the island's current status as a U.S. commonwealth and, if not, whether they would prefer statehood, independence or an undefined "enhanced" commonwealth relationship.
The PPD wants Puerto Rico to remain a commonwealth, though with greater autonomy, but the governor's New Progressive Party favors statehood.
Puerto Ricans have gone to the polls three times in the past 45 years to weigh in on the status question.
The first referendum, in 1967, produced a majority of just over 60 percent in favor of remaining a U.S. commonwealth. In 1993, support for commonwealth status had shrunk to a 48.6 percent plurality.
Five years later, 50.3 percent of Puerto Ricans casting ballots rejected all three options - statehood, independence and commonwealth - and checked the box marked "none of the above."
Puerto Rico came under Washington's sway in 1898 and island residents were granted U.S. citizenship in 1917, yet they cannot vote in presidential elections, though Puerto Ricans living in the continental United States can.
Since 1952, the island has been a self-governing, unincorporated territory of the United States with broad internal autonomy, but without the right to conduct its own foreign policy.