Black firefighters brought a discrimination suit against the City of Birmingham, Alabama (D). It was settled by a consent decree; affirmative action programs were mandated. Several white firefighters, Martin (P), then sued under civil rights laws contending that the affirmative action programs constituted reverse discrimination as the promotions of the black firefighters were based on race. D defended on grounds that the consent judgment precluded P’s suit. The district court dismissed P’s suit; the prior judgment had a preclusive effect. The court of appeals reversed rejecting the 'impermissible collateral attack' doctrine that immunizes parties to a consent decree from discrimination charges by nonparties for actions taken pursuant to the decree.