WASHINGTON (AP) The Supreme Court ruled unanimously Monday that workers who cooperate with internal investigations of retaliation by their employers are sheltered by federal laws prohibiting job discrimination.

In the opinion, the justices held that a longtime school system employee in Tennessee can pursue a civil rights lawsuit over her firing.

The court voted to reverse the 6th U.S. Circuit Court of Appeals' ruling that the anti-retaliation provision of Title VII of the 1964 Civil Rights Act does not apply to employees who merely cooperate with an internal probe rather than complain on their own or take part in a formal investigation.

"The question here is whether this protection extends to an employee who speaks out about discrimination not on her own initiative, but in answering questions during an employer's internal investigation. We hold that it does," Justice David Souter said for the court.

Vicky Crawford was fired in 2003 after more than 30 years as an employee of the school system for Nashville, Tenn., and Davidson County.

She did not file a complaint about harassment by a school official. But she said she had been subjected to unwanted sexual advances when she was interviewed by investigators for the school system who were looking into other employees' allegations against the director of employee relations.

Crawford related instances in which the school district's employee relations director, Gene Hughes, allegedly put his crotch up to her office window and entered her office, grabbed her head and pulled it to his crotch, Souter said in his opinion.

The school system took no action against Hughes. Crawford was fired months later.

She filed a federal lawsuit, but it was dismissed by a federal judge and upheld on appeal.

The Bush administration backed Crawford in her appeal to the Supreme Court.

Ann Steiner, Crawford's attorney, said the ruling is a "great win for civil rights."

"It means from this point on no matter who instigates an investigation or conversation about harassment, if someone communicates that they've been harassed, they'll be protected under the retaliation provisions," Steiner said.

The school system and business interests argued that if employees like Crawford are covered by Title VII's anti-retaliation provisions, employers will refrain from launching internal investigations.

"The argument is unconvincing," Souter said. Employers already have strong incentives to "ferret out" discriminatory activity as a way to limit their liability, he said.

Officials with the Nashville school system didn't immediately return calls seeking comment.

The civil rights law's anti-retaliation section protects employees who complain about, or oppose, discrimination as well as those who participate in formal investigations. The court limited its ruling to the opposition clause and did not pass judgment on whether Crawford also is protected under the participation clause.

The school system has said that Crawford was fired over charges of irregularities in her job as payroll coordinator. It also has other arguments defending itself from the retaliation claim. The case is being sent back to the appeals court to consider those issues.

The case is Crawford v. Metropolitan Government of Nashville and Davidson County, Tenn., 06-1595.

Copyright 2009 The Associated Press.