Workers who cooperate with their employers' internal investigations of discrimination may not be fired in retaliation for implicating colleagues or superiors, a unanimous Supreme Court ruled Monday.

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 Cincinnati-based court was alone among federal appeals courts in its narrow view of the civil rights law, which was already understood to bar retaliation against people who complained about harassment and other discrimination.

"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.