Usain Bolt won't be getting back his ninth Olympic gold medal.

The Court of Arbitration for Sport says its judging panel dismissed Jamaican sprinter Nesta Carter's appeal against disqualification from the 2008 Beijing Olympics for a positive doping test discovered eight years later.

Carter ran the opening leg in the 4x100-meter relay when Bolt took the baton third and helped Jamaica win in a world record of 37.10 seconds.

In fresh analysis of Beijing samples by the International Olympic Committee in 2016, Carter tested positive for the stimulant methylhexaneamine. Jamaica was disqualified and stripped of the relay title.

The case spoils Bolt's perfect Olympic career of three gold medals in the 100, 200 and 4x100 at three consecutive games in 2008, 2012 and 2016.