The ADA forbids employers from retaliating against a person who has opposed any act or practice made unlawful by the federal law or because an individual has “made a charge, testified, assisted, or participated in any manner in an investigation, proceeding, or hearing” under the federal law. In general, when workers complain about discrimination or harassment or participate in an internal investigation into alleged misconduct, they are engaging in protected activity. The appeals court in this case noted that it and other courts have held that advocating for members of a protected class is a protected activity.
