Antonio McKay, a two-time Olympic relay gold medalist suspended by The Athletics Congress for three months for using stimulants, has been cleared by an appeals panel.
McKay tested positive in January for the banned stimulant phenylpropanalomine that is commonly found in cold medicines.
Charles Desjardins, chairman of the three-person panel, was quoted in USA Today as saying that part of McKay's defense was that neither he nor his doctor realized medication prescribed for the flu contained the banned substance.
Rules adopted by the sport's national governing body contain a provision that such ignorance is not a valid excuse.
"I can't understand how they overturned the decision to suspend," TAC President Frank Greenburg said.