At the 2009 Jamaica National Championships, Blackwood tried for a spot at the 2009 World Championships in Athletics, but was disqualified running outside his lane in the semi-finals of the 400 m. In August, he announced his retirement from the sport.
In 2009 American sprinter Jerome Young admitted to doping during the period of 1999 through 2003. The IAAF gave Young a life ban as a result and annulled his performances. This had a significant effect on Blackwoods career: Jamaica were elevated to World Indoor 4x400 m Relay gold medal, where Blackwood ran the third leg. He was given the 400 m bronze medal at the 2003 World Championships, as well as being moved up to the top spot at the 2003 World Athletics Final.