Tariq Ramadan, a professor sympathetic to Palestinian resistance to Israel, had his U.S. visa revoked in 2004 as he was about to take a tenured teaching job at the University of Notre Dame in Indiana.

His subsequent applications for a new visa were denied on the grounds that he had donated $1,336 to a charity that gave money to Hamas, which has been designated a terrorist organization by the U.S.

The 2nd U.S. Circuit Court of Appeals ruled Friday that it was legal for the government to bar Ramadan from the country, but said it had an obligation to inform him of the concerns about his donations and give him a chance to prove he didn't know his money would go to Hamas.

The three-judge panel said it was possible that a consular official had, in fact, given him that opportunity, but there was no record of it before the court.

The case will now return to a lower court and the government will be given a chance to figure out more about the exact details of the conversations between Ramadan and the consular staff in Bern, Switzerland that handled his visa application.

Ramadan could also reapply for the visa, the court said.

Jameel Jaffer, the American Civil Liberties Union lawyer who argued Ramadan's case before the appeals court, said he was hopeful the Obama administration would allow the professor to enter the U.S. without further litigation.

"Over the next few weeks, we'll be encouraging the administration to take a new look not only at Ramadan's case but at the cases of other foreign scholars and writers who were excluded by the Bush administration on ideological grounds," he said.