"It's a crushing blow," Canadian Council for Refugees executive director Janet Dench told The Catholic Register.

The church and human rights groups began their legal challenge to the Canada-U.S. refugee treaty in 2005. They argued that the Americans have consistently barred refugees from certain countries — among them Haiti, Colombia and the Central American countries — from applying for refugee status. The end result is that the United States has deported people back to their home countries to face torture, imprisonment and death, the groups say.

In 2007 the Federal Court of Canada ruled the United States was not in fact a safe country for all refugees, effectively striking down the treaty. Last June, the Federal Court of Appeals overturned that decision, ruling that the court did not have jurisdiction to nullify the federal cabinet's finding that the United States is in compliance with the United Nations Convention Against Torture and the United Nations Convention Relating to the Status of Refugees, international treaties which both Canada and the United States have ratified.

In September the refugee advocates were sure that the Supreme Court would hear an appeal and hoped the court would rule on substance rather than procedure.

"The only court that has ruled on this was the first level court, Justice (Michael) Phelan. He found the U.S. does not comply with its international obligations," said Dench. "We will be looking to see if there are other ways of bringing this issue to the court."

As is usual, the Supreme Court gave no reasons for turning down the appeal.

The refugee rights' organizations also hope to build political opposition to the Safe Third Country Agreement.

"We're not going to let this issue die," Dench said. "Once we've recovered from the first effect of the shock we're going to be looking at other options for advancing the rights of refugees."