SANTA ANA, Calif. — A federal appeals court panel Friday revived a lawsuit alleging the FBI violated the civil rights of Southland Muslims by using an undercover operative to infiltrate Orange County mosques, more than a decade after the case was dismissed on grounds it would endanger national security if the case went to trial.

The lawsuit, filed in 2011 on behalf of Yassir Fazaga, Ali Uddin Malik and Yasser AbdelRahim, centers on ex-FBI informant Craig Monteilh, who said he was recruited by the federal agency to pretend he was a Muslim convert and infiltrate Orange County mosques to gather information and point out extremists.

The following year, U.S. District Judge Cormac Carney dismissed the bulk of the case, accepting defense arguments that the case could not move forward without revealing state secrets.

The case then bounced around the federal appeals system, and on Friday, a three-judge panel of the 9th U.S. Circuit Court of Appeals reversed the dismissal on state secrets grounds, saying that argument could not be used to dismiss claims that the plaintiffs were improperly targeted because of their religion.

The panel noted that while there was some privileged information included in the case, "the district court did not apply the proper standard or use the proper process when it held that Fazaga's religion claims should be dismissed outright on the grounds that privileged information gives defendants a valid defense, and that litigation would present an unacceptable risk of disclosing state secrets."

"The district court has not yet conducted the detailed and fact- intensive inquiry required to dismiss a claim based on a valid defense under (a state secrets claim), nor did the district court's dismissal of Fazaga's claims on the basis that litigation would present an unacceptable risk of disclosing state secrets meet the stringent standard for such dismissals," according to the ruling.

The panel remanded the case back to the federal district court for further proceedings. 

In a statement released by the ACLU of Southern California, Fazaga — former imam of the Orange County Islamic Foundation, hailed the ruling.

"Nearly two decades ago, the FBI sent an informant to Orange County to surveil and harass our sacred community," Fazaga said. "Ali, Yasser and I decided to fight back, and after today's ruling, we will have the courthouse doors finally opened to us. We and the thousands of Muslims whom the FBI targeted simply for praying in mosques deserve justice."

The suit alleged that Monteilh violated the constitutional rights of Muslims by infiltrating mosques and recording conversations in a search for potential terrorists. The lawsuit contended that over 14 months, beginning in 2006, the FBI used Monteilh to "indiscriminately" collect personal information on hundreds or even thousands of Muslim Americans.

Monteilh, who served time in prison for forgery, claimed he was recruited by the FBI in 2004 to infiltrate drug-trafficking groups, according to the lawsuit. In 2006, he said, he was asked to assume the identity of a Muslim convert and go undercover to identify extremists and gather intelligence; the suit contends.

"Today, the Ninth Circuit said that the government does not get a free pass out of wrongdoing simply by shouting `national security,"' Mohammad Tajsar, senior staff attorney at the ACLU SoCal, said in a statement. "Today's victory ensures our clients will get their day in court."