The length of the ban was determined by an arbitration panel of three officials in the United States and is half the term initially suggested by the US Anti-Doping Agency. It also represents a let-off from the lifetime ban that could have been imposed because this was Gatlin's second doping offence.
As a student, the sprinter had tested positive for a banned stimulant. He was given a two-year ban, which was halved when it was established that the drug had been contained in medication he used to combat attention deficit disorder.
The International Association of Athletics Federations stipulated at the time, however, that a second doping violation would mean a lifetime ban.
Gatlin confessed that he had tested positive for the banned hormone testosterone at the low-key Kansas Relays meeting in April 2006.
The revelation came as a shock since Gatlin, an outspoken critic of drugs, appeared to have the world at his feet. He was the Olympic champion, the world champion at 100m and 200m and had equalled Asafa Powell's world 100m record of 9.77 sec.
The only questions being asked about Gatlin at that time were about his association with Trevor Graham, the North Carolina coach of several athletes who had been involved in the Balco doping scandal.
The most notable of these was Marion Jones, who confessed to using drugs before pleading guilty in October to lying to federal investigators.
Gatlin readily accepted that he had committed a doping offence in 2006 but claimed in his appeal for a reduction that he had been the victim of sabotage when a masseur had rubbed testosterone cream onto his legs. The allegation was denied by the masseur. Gatlin also believed that his previous doping ban should not be held against him.
A four-year ban ends any hope Gatlin had of defending his Olympic 100m title in Beijing in August.
If there is a lifeline for the 25-year-old, it is in the Court of Arbitration for Sport in Lausanne. The disgraced sprinter can launch an appeal against the ban to the CAS, whose decision is final and binding. However, the IAAF would not let any action by Gatlin go unchallenged.